Initial import

1 files changed, 692 insertions, 0 deletions

diff --git a/fs/nfsd/nfsfh.c b/fs/nfsd/nfsfh.c
new file mode 100644
index 000000000..350041a40
--- /dev/null
+++ b/fs/nfsd/nfsfh.c
@@ -0,0 +1,692 @@
+/*
+ * NFS server file handle treatment.
+ *
+ * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
+ * Portions Copyright (C) 1999 G. Allen Morris III <gam3@acm.org>
+ * Extensive rewrite by Neil Brown <neilb@cse.unsw.edu.au> Southern-Spring 1999
+ * ... and again Southern-Winter 2001 to support export_operations
+ */
+
+#include <linux/exportfs.h>
+
+#include <linux/sunrpc/svcauth_gss.h>
+#include "nfsd.h"
+#include "vfs.h"
+#include "auth.h"
+
+#define NFSDDBG_FACILITY		NFSDDBG_FH
+
+
+/*
+ * our acceptability function.
+ * if NOSUBTREECHECK, accept anything
+ * if not, require that we can walk up to exp->ex_dentry
+ * doing some checks on the 'x' bits
+ */
+static int nfsd_acceptable(void *expv, struct dentry *dentry)
+{
+	struct svc_export *exp = expv;
+	int rv;
+	struct dentry *tdentry;
+	struct dentry *parent;
+
+	if (exp->ex_flags & NFSEXP_NOSUBTREECHECK)
+		return 1;
+
+	tdentry = dget(dentry);
+	while (tdentry != exp->ex_path.dentry && !IS_ROOT(tdentry)) {
+		/* make sure parents give x permission to user */
+		int err;
+		parent = dget_parent(tdentry);
+		err = inode_permission(d_inode(parent), MAY_EXEC);
+		if (err < 0) {
+			dput(parent);
+			break;
+		}
+		dput(tdentry);
+		tdentry = parent;
+	}
+	if (tdentry != exp->ex_path.dentry)
+		dprintk("nfsd_acceptable failed at %p %pd\n", tdentry, tdentry);
+	rv = (tdentry == exp->ex_path.dentry);
+	dput(tdentry);
+	return rv;
+}
+
+/* Type check. The correct error return for type mismatches does not seem to be
+ * generally agreed upon. SunOS seems to use EISDIR if file isn't S_IFREG; a
+ * comment in the NFSv3 spec says this is incorrect (implementation notes for
+ * the write call).
+ */
+static inline __be32
+nfsd_mode_check(struct svc_rqst *rqstp, umode_t mode, umode_t requested)
+{
+	mode &= S_IFMT;
+
+	if (requested == 0) /* the caller doesn't care */
+		return nfs_ok;
+	if (mode == requested)
+		return nfs_ok;
+	/*
+	 * v4 has an error more specific than err_notdir which we should
+	 * return in preference to err_notdir:
+	 */
+	if (rqstp->rq_vers == 4 && mode == S_IFLNK)
+		return nfserr_symlink;
+	if (requested == S_IFDIR)
+		return nfserr_notdir;
+	if (mode == S_IFDIR)
+		return nfserr_isdir;
+	return nfserr_inval;
+}
+
+static __be32 nfsd_setuser_and_check_port(struct svc_rqst *rqstp,
+					  struct svc_export *exp)
+{
+	int flags = nfsexp_flags(rqstp, exp);
+
+	/* Check if the request originated from a secure port. */
+	if (!test_bit(RQ_SECURE, &rqstp->rq_flags) && !(flags & NFSEXP_INSECURE_PORT)) {
+		RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);
+		dprintk("nfsd: request from insecure port %s!\n",
+		        svc_print_addr(rqstp, buf, sizeof(buf)));
+		return nfserr_perm;
+	}
+
+	/* Set user creds for this exportpoint */
+	return nfserrno(nfsd_setuser(rqstp, exp));
+}
+
+static inline __be32 check_pseudo_root(struct svc_rqst *rqstp,
+	struct dentry *dentry, struct svc_export *exp)
+{
+	if (!(exp->ex_flags & NFSEXP_V4ROOT))
+		return nfs_ok;
+	/*
+	 * v2/v3 clients have no need for the V4ROOT export--they use
+	 * the mount protocl instead; also, further V4ROOT checks may be
+	 * in v4-specific code, in which case v2/v3 clients could bypass
+	 * them.
+	 */
+	if (!nfsd_v4client(rqstp))
+		return nfserr_stale;
+	/*
+	 * We're exposing only the directories and symlinks that have to be
+	 * traversed on the way to real exports:
+	 */
+	if (unlikely(!d_is_dir(dentry) &&
+		     !d_is_symlink(dentry)))
+		return nfserr_stale;
+	/*
+	 * A pseudoroot export gives permission to access only one
+	 * single directory; the kernel has to make another upcall
+	 * before granting access to anything else under it:
+	 */
+	if (unlikely(dentry != exp->ex_path.dentry))
+		return nfserr_stale;
+	return nfs_ok;
+}
+
+/*
+ * Use the given filehandle to look up the corresponding export and
+ * dentry.  On success, the results are used to set fh_export and
+ * fh_dentry.
+ */
+static __be32 nfsd_set_fh_dentry(struct svc_rqst *rqstp, struct svc_fh *fhp)
+{
+	struct knfsd_fh	*fh = &fhp->fh_handle;
+	struct fid *fid = NULL, sfid;
+	struct svc_export *exp;
+	struct dentry *dentry;
+	int fileid_type;
+	int data_left = fh->fh_size/4;
+	__be32 error;
+
+	error = nfserr_stale;
+	if (rqstp->rq_vers > 2)
+		error = nfserr_badhandle;
+	if (rqstp->rq_vers == 4 && fh->fh_size == 0)
+		return nfserr_nofilehandle;
+
+	if (fh->fh_version == 1) {
+		int len;
+
+		if (--data_left < 0)
+			return error;
+		if (fh->fh_auth_type != 0)
+			return error;
+		len = key_len(fh->fh_fsid_type) / 4;
+		if (len == 0)
+			return error;
+		if  (fh->fh_fsid_type == FSID_MAJOR_MINOR) {
+			/* deprecated, convert to type 3 */
+			len = key_len(FSID_ENCODE_DEV)/4;
+			fh->fh_fsid_type = FSID_ENCODE_DEV;
+			/*
+			 * struct knfsd_fh uses host-endian fields, which are
+			 * sometimes used to hold net-endian values. This
+			 * confuses sparse, so we must use __force here to
+			 * keep it from complaining.
+			 */
+			fh->fh_fsid[0] = new_encode_dev(MKDEV(ntohl((__force __be32)fh->fh_fsid[0]),
+							ntohl((__force __be32)fh->fh_fsid[1])));
+			fh->fh_fsid[1] = fh->fh_fsid[2];
+		}
+		data_left -= len;
+		if (data_left < 0)
+			return error;
+		exp = rqst_exp_find(rqstp, fh->fh_fsid_type, fh->fh_fsid);
+		fid = (struct fid *)(fh->fh_fsid + len);
+	} else {
+		__u32 tfh[2];
+		dev_t xdev;
+		ino_t xino;
+
+		if (fh->fh_size != NFS_FHSIZE)
+			return error;
+		/* assume old filehandle format */
+		xdev = old_decode_dev(fh->ofh_xdev);
+		xino = u32_to_ino_t(fh->ofh_xino);
+		mk_fsid(FSID_DEV, tfh, xdev, xino, 0, NULL);
+		exp = rqst_exp_find(rqstp, FSID_DEV, tfh);
+	}
+
+	error = nfserr_stale;
+	if (PTR_ERR(exp) == -ENOENT)
+		return error;
+
+	if (IS_ERR(exp))
+		return nfserrno(PTR_ERR(exp));
+
+	if (exp->ex_flags & NFSEXP_NOSUBTREECHECK) {
+		/* Elevate privileges so that the lack of 'r' or 'x'
+		 * permission on some parent directory will
+		 * not stop exportfs_decode_fh from being able
+		 * to reconnect a directory into the dentry cache.
+		 * The same problem can affect "SUBTREECHECK" exports,
+		 * but as nfsd_acceptable depends on correct
+		 * access control settings being in effect, we cannot
+		 * fix that case easily.
+		 */
+		struct cred *new = prepare_creds();
+		if (!new) {
+			error =  nfserrno(-ENOMEM);
+			goto out;
+		}
+		new->cap_effective =
+			cap_raise_nfsd_set(new->cap_effective,
+					   new->cap_permitted);
+		put_cred(override_creds(new));
+		put_cred(new);
+	} else {
+		error = nfsd_setuser_and_check_port(rqstp, exp);
+		if (error)
+			goto out;
+	}
+
+	/*
+	 * Look up the dentry using the NFS file handle.
+	 */
+	error = nfserr_stale;
+	if (rqstp->rq_vers > 2)
+		error = nfserr_badhandle;
+
+	if (fh->fh_version != 1) {
+		sfid.i32.ino = fh->ofh_ino;
+		sfid.i32.gen = fh->ofh_generation;
+		sfid.i32.parent_ino = fh->ofh_dirino;
+		fid = &sfid;
+		data_left = 3;
+		if (fh->ofh_dirino == 0)
+			fileid_type = FILEID_INO32_GEN;
+		else
+			fileid_type = FILEID_INO32_GEN_PARENT;
+	} else
+		fileid_type = fh->fh_fileid_type;
+
+	if (fileid_type == FILEID_ROOT)
+		dentry = dget(exp->ex_path.dentry);
+	else {
+		dentry = exportfs_decode_fh(exp->ex_path.mnt, fid,
+				data_left, fileid_type,
+				nfsd_acceptable, exp);
+	}
+	if (dentry == NULL)
+		goto out;
+	if (IS_ERR(dentry)) {
+		if (PTR_ERR(dentry) != -EINVAL)
+			error = nfserrno(PTR_ERR(dentry));
+		goto out;
+	}
+
+	if (d_is_dir(dentry) &&
+			(dentry->d_flags & DCACHE_DISCONNECTED)) {
+		printk("nfsd: find_fh_dentry returned a DISCONNECTED directory: %pd2\n",
+				dentry);
+	}
+
+	fhp->fh_dentry = dentry;
+	fhp->fh_export = exp;
+	return 0;
+out:
+	exp_put(exp);
+	return error;
+}
+
+/**
+ * fh_verify - filehandle lookup and access checking
+ * @rqstp: pointer to current rpc request
+ * @fhp: filehandle to be verified
+ * @type: expected type of object pointed to by filehandle
+ * @access: type of access needed to object
+ *
+ * Look up a dentry from the on-the-wire filehandle, check the client's
+ * access to the export, and set the current task's credentials.
+ *
+ * Regardless of success or failure of fh_verify(), fh_put() should be
+ * called on @fhp when the caller is finished with the filehandle.
+ *
+ * fh_verify() may be called multiple times on a given filehandle, for
+ * example, when processing an NFSv4 compound.  The first call will look
+ * up a dentry using the on-the-wire filehandle.  Subsequent calls will
+ * skip the lookup and just perform the other checks and possibly change
+ * the current task's credentials.
+ *
+ * @type specifies the type of object expected using one of the S_IF*
+ * constants defined in include/linux/stat.h.  The caller may use zero
+ * to indicate that it doesn't care, or a negative integer to indicate
+ * that it expects something not of the given type.
+ *
+ * @access is formed from the NFSD_MAY_* constants defined in
+ * include/linux/nfsd/nfsd.h.
+ */
+__be32
+fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type, int access)
+{
+	struct svc_export *exp;
+	struct dentry	*dentry;
+	__be32		error;
+
+	dprintk("nfsd: fh_verify(%s)\n", SVCFH_fmt(fhp));
+
+	if (!fhp->fh_dentry) {
+		error = nfsd_set_fh_dentry(rqstp, fhp);
+		if (error)
+			goto out;
+	}
+	dentry = fhp->fh_dentry;
+	exp = fhp->fh_export;
+	/*
+	 * We still have to do all these permission checks, even when
+	 * fh_dentry is already set:
+	 * 	- fh_verify may be called multiple times with different
+	 * 	  "access" arguments (e.g. nfsd_proc_create calls
+	 * 	  fh_verify(...,NFSD_MAY_EXEC) first, then later (in
+	 * 	  nfsd_create) calls fh_verify(...,NFSD_MAY_CREATE).
+	 *	- in the NFSv4 case, the filehandle may have been filled
+	 *	  in by fh_compose, and given a dentry, but further
+	 *	  compound operations performed with that filehandle
+	 *	  still need permissions checks.  In the worst case, a
+	 *	  mountpoint crossing may have changed the export
+	 *	  options, and we may now need to use a different uid
+	 *	  (for example, if different id-squashing options are in
+	 *	  effect on the new filesystem).
+	 */
+	error = check_pseudo_root(rqstp, dentry, exp);
+	if (error)
+		goto out;
+
+	error = nfsd_setuser_and_check_port(rqstp, exp);
+	if (error)
+		goto out;
+
+	error = nfsd_mode_check(rqstp, d_inode(dentry)->i_mode, type);
+	if (error)
+		goto out;
+
+	/*
+	 * pseudoflavor restrictions are not enforced on NLM,
+	 * which clients virtually always use auth_sys for,
+	 * even while using RPCSEC_GSS for NFS.
+	 */
+	if (access & NFSD_MAY_LOCK || access & NFSD_MAY_BYPASS_GSS)
+		goto skip_pseudoflavor_check;
+	/*
+	 * Clients may expect to be able to use auth_sys during mount,
+	 * even if they use gss for everything else; see section 2.3.2
+	 * of rfc 2623.
+	 */
+	if (access & NFSD_MAY_BYPASS_GSS_ON_ROOT
+			&& exp->ex_path.dentry == dentry)
+		goto skip_pseudoflavor_check;
+
+	error = check_nfsd_access(exp, rqstp);
+	if (error)
+		goto out;
+
+skip_pseudoflavor_check:
+	/* Finally, check access permissions. */
+	error = nfsd_permission(rqstp, exp, dentry, access);
+
+	if (error) {
+		dprintk("fh_verify: %pd2 permission failure, "
+			"acc=%x, error=%d\n",
+			dentry,
+			access, ntohl(error));
+	}
+out:
+	if (error == nfserr_stale)
+		nfsdstats.fh_stale++;
+	return error;
+}
+
+
+/*
+ * Compose a file handle for an NFS reply.
+ *
+ * Note that when first composed, the dentry may not yet have
+ * an inode.  In this case a call to fh_update should be made
+ * before the fh goes out on the wire ...
+ */
+static void _fh_update(struct svc_fh *fhp, struct svc_export *exp,
+		struct dentry *dentry)
+{
+	if (dentry != exp->ex_path.dentry) {
+		struct fid *fid = (struct fid *)
+			(fhp->fh_handle.fh_fsid + fhp->fh_handle.fh_size/4 - 1);
+		int maxsize = (fhp->fh_maxsize - fhp->fh_handle.fh_size)/4;
+		int subtreecheck = !(exp->ex_flags & NFSEXP_NOSUBTREECHECK);
+
+		fhp->fh_handle.fh_fileid_type =
+			exportfs_encode_fh(dentry, fid, &maxsize, subtreecheck);
+		fhp->fh_handle.fh_size += maxsize * 4;
+	} else {
+		fhp->fh_handle.fh_fileid_type = FILEID_ROOT;
+	}
+}
+
+/*
+ * for composing old style file handles
+ */
+static inline void _fh_update_old(struct dentry *dentry,
+				  struct svc_export *exp,
+				  struct knfsd_fh *fh)
+{
+	fh->ofh_ino = ino_t_to_u32(d_inode(dentry)->i_ino);
+	fh->ofh_generation = d_inode(dentry)->i_generation;
+	if (d_is_dir(dentry) ||
+	    (exp->ex_flags & NFSEXP_NOSUBTREECHECK))
+		fh->ofh_dirino = 0;
+}
+
+static bool is_root_export(struct svc_export *exp)
+{
+	return exp->ex_path.dentry == exp->ex_path.dentry->d_sb->s_root;
+}
+
+static struct super_block *exp_sb(struct svc_export *exp)
+{
+	return d_inode(exp->ex_path.dentry)->i_sb;
+}
+
+static bool fsid_type_ok_for_exp(u8 fsid_type, struct svc_export *exp)
+{
+	switch (fsid_type) {
+	case FSID_DEV:
+		if (!old_valid_dev(exp_sb(exp)->s_dev))
+			return 0;
+		/* FALL THROUGH */
+	case FSID_MAJOR_MINOR:
+	case FSID_ENCODE_DEV:
+		return exp_sb(exp)->s_type->fs_flags & FS_REQUIRES_DEV;
+	case FSID_NUM:
+		return exp->ex_flags & NFSEXP_FSID;
+	case FSID_UUID8:
+	case FSID_UUID16:
+		if (!is_root_export(exp))
+			return 0;
+		/* fall through */
+	case FSID_UUID4_INUM:
+	case FSID_UUID16_INUM:
+		return exp->ex_uuid != NULL;
+	}
+	return 1;
+}
+
+
+static void set_version_and_fsid_type(struct svc_fh *fhp, struct svc_export *exp, struct svc_fh *ref_fh)
+{
+	u8 version;
+	u8 fsid_type;
+retry:
+	version = 1;
+	if (ref_fh && ref_fh->fh_export == exp) {
+		version = ref_fh->fh_handle.fh_version;
+		fsid_type = ref_fh->fh_handle.fh_fsid_type;
+
+		ref_fh = NULL;
+
+		switch (version) {
+		case 0xca:
+			fsid_type = FSID_DEV;
+			break;
+		case 1:
+			break;
+		default:
+			goto retry;
+		}
+
+		/*
+		 * As the fsid -> filesystem mapping was guided by
+		 * user-space, there is no guarantee that the filesystem
+		 * actually supports that fsid type. If it doesn't we
+		 * loop around again without ref_fh set.
+		 */
+		if (!fsid_type_ok_for_exp(fsid_type, exp))
+			goto retry;
+	} else if (exp->ex_flags & NFSEXP_FSID) {
+		fsid_type = FSID_NUM;
+	} else if (exp->ex_uuid) {
+		if (fhp->fh_maxsize >= 64) {
+			if (is_root_export(exp))
+				fsid_type = FSID_UUID16;
+			else
+				fsid_type = FSID_UUID16_INUM;
+		} else {
+			if (is_root_export(exp))
+				fsid_type = FSID_UUID8;
+			else
+				fsid_type = FSID_UUID4_INUM;
+		}
+	} else if (!old_valid_dev(exp_sb(exp)->s_dev))
+		/* for newer device numbers, we must use a newer fsid format */
+		fsid_type = FSID_ENCODE_DEV;
+	else
+		fsid_type = FSID_DEV;
+	fhp->fh_handle.fh_version = version;
+	if (version)
+		fhp->fh_handle.fh_fsid_type = fsid_type;
+}
+
+__be32
+fh_compose(struct svc_fh *fhp, struct svc_export *exp, struct dentry *dentry,
+	   struct svc_fh *ref_fh)
+{
+	/* ref_fh is a reference file handle.
+	 * if it is non-null and for the same filesystem, then we should compose
+	 * a filehandle which is of the same version, where possible.
+	 * Currently, that means that if ref_fh->fh_handle.fh_version == 0xca
+	 * Then create a 32byte filehandle using nfs_fhbase_old
+	 *
+	 */
+
+	struct inode * inode = d_inode(dentry);
+	dev_t ex_dev = exp_sb(exp)->s_dev;
+
+	dprintk("nfsd: fh_compose(exp %02x:%02x/%ld %pd2, ino=%ld)\n",
+		MAJOR(ex_dev), MINOR(ex_dev),
+		(long) d_inode(exp->ex_path.dentry)->i_ino,
+		dentry,
+		(inode ? inode->i_ino : 0));
+
+	/* Choose filehandle version and fsid type based on
+	 * the reference filehandle (if it is in the same export)
+	 * or the export options.
+	 */
+	 set_version_and_fsid_type(fhp, exp, ref_fh);
+
+	if (ref_fh == fhp)
+		fh_put(ref_fh);
+
+	if (fhp->fh_locked || fhp->fh_dentry) {
+		printk(KERN_ERR "fh_compose: fh %pd2 not initialized!\n",
+		       dentry);
+	}
+	if (fhp->fh_maxsize < NFS_FHSIZE)
+		printk(KERN_ERR "fh_compose: called with maxsize %d! %pd2\n",
+		       fhp->fh_maxsize,
+		       dentry);
+
+	fhp->fh_dentry = dget(dentry); /* our internal copy */
+	fhp->fh_export = exp_get(exp);
+
+	if (fhp->fh_handle.fh_version == 0xca) {
+		/* old style filehandle please */
+		memset(&fhp->fh_handle.fh_base, 0, NFS_FHSIZE);
+		fhp->fh_handle.fh_size = NFS_FHSIZE;
+		fhp->fh_handle.ofh_dcookie = 0xfeebbaca;
+		fhp->fh_handle.ofh_dev =  old_encode_dev(ex_dev);
+		fhp->fh_handle.ofh_xdev = fhp->fh_handle.ofh_dev;
+		fhp->fh_handle.ofh_xino =
+			ino_t_to_u32(d_inode(exp->ex_path.dentry)->i_ino);
+		fhp->fh_handle.ofh_dirino = ino_t_to_u32(parent_ino(dentry));
+		if (inode)
+			_fh_update_old(dentry, exp, &fhp->fh_handle);
+	} else {
+		fhp->fh_handle.fh_size =
+			key_len(fhp->fh_handle.fh_fsid_type) + 4;
+		fhp->fh_handle.fh_auth_type = 0;
+
+		mk_fsid(fhp->fh_handle.fh_fsid_type,
+			fhp->fh_handle.fh_fsid,
+			ex_dev,
+			d_inode(exp->ex_path.dentry)->i_ino,
+			exp->ex_fsid, exp->ex_uuid);
+
+		if (inode)
+			_fh_update(fhp, exp, dentry);
+		if (fhp->fh_handle.fh_fileid_type == FILEID_INVALID) {
+			fh_put(fhp);
+			return nfserr_opnotsupp;
+		}
+	}
+
+	return 0;
+}
+
+/*
+ * Update file handle information after changing a dentry.
+ * This is only called by nfsd_create, nfsd_create_v3 and nfsd_proc_create
+ */
+__be32
+fh_update(struct svc_fh *fhp)
+{
+	struct dentry *dentry;
+
+	if (!fhp->fh_dentry)
+		goto out_bad;
+
+	dentry = fhp->fh_dentry;
+	if (d_really_is_negative(dentry))
+		goto out_negative;
+	if (fhp->fh_handle.fh_version != 1) {
+		_fh_update_old(dentry, fhp->fh_export, &fhp->fh_handle);
+	} else {
+		if (fhp->fh_handle.fh_fileid_type != FILEID_ROOT)
+			return 0;
+
+		_fh_update(fhp, fhp->fh_export, dentry);
+		if (fhp->fh_handle.fh_fileid_type == FILEID_INVALID)
+			return nfserr_opnotsupp;
+	}
+	return 0;
+out_bad:
+	printk(KERN_ERR "fh_update: fh not verified!\n");
+	return nfserr_serverfault;
+out_negative:
+	printk(KERN_ERR "fh_update: %pd2 still negative!\n",
+		dentry);
+	return nfserr_serverfault;
+}
+
+/*
+ * Release a file handle.
+ */
+void
+fh_put(struct svc_fh *fhp)
+{
+	struct dentry * dentry = fhp->fh_dentry;
+	struct svc_export * exp = fhp->fh_export;
+	if (dentry) {
+		fh_unlock(fhp);
+		fhp->fh_dentry = NULL;
+		dput(dentry);
+#ifdef CONFIG_NFSD_V3
+		fhp->fh_pre_saved = 0;
+		fhp->fh_post_saved = 0;
+#endif
+	}
+	fh_drop_write(fhp);
+	if (exp) {
+		exp_put(exp);
+		fhp->fh_export = NULL;
+	}
+	return;
+}
+
+/*
+ * Shorthand for dprintk()'s
+ */
+char * SVCFH_fmt(struct svc_fh *fhp)
+{
+	struct knfsd_fh *fh = &fhp->fh_handle;
+
+	static char buf[80];
+	sprintf(buf, "%d: %08x %08x %08x %08x %08x %08x",
+		fh->fh_size,
+		fh->fh_base.fh_pad[0],
+		fh->fh_base.fh_pad[1],
+		fh->fh_base.fh_pad[2],
+		fh->fh_base.fh_pad[3],
+		fh->fh_base.fh_pad[4],
+		fh->fh_base.fh_pad[5]);
+	return buf;
+}
+
+enum fsid_source fsid_source(struct svc_fh *fhp)
+{
+	if (fhp->fh_handle.fh_version != 1)
+		return FSIDSOURCE_DEV;
+	switch(fhp->fh_handle.fh_fsid_type) {
+	case FSID_DEV:
+	case FSID_ENCODE_DEV:
+	case FSID_MAJOR_MINOR:
+		if (exp_sb(fhp->fh_export)->s_type->fs_flags & FS_REQUIRES_DEV)
+			return FSIDSOURCE_DEV;
+		break;
+	case FSID_NUM:
+		if (fhp->fh_export->ex_flags & NFSEXP_FSID)
+			return FSIDSOURCE_FSID;
+		break;
+	default:
+		break;
+	}
+	/* either a UUID type filehandle, or the filehandle doesn't
+	 * match the export.
+	 */
+	if (fhp->fh_export->ex_flags & NFSEXP_FSID)
+		return FSIDSOURCE_FSID;
+	if (fhp->fh_export->ex_uuid)
+		return FSIDSOURCE_UUID;
+	return FSIDSOURCE_DEV;
+}