fs/nfsd/nfsfh.c - kernel/msm-4.9 - Gitiles

 /*
  * linux/fs/nfsd/nfsfh.c
  *
  * 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/slab.h>
 #include <linux/fs.h>
 #include <linux/unistd.h>
 #include <linux/string.h>
 #include <linux/stat.h>
 #include <linux/dcache.h>
 #include <linux/mount.h>

 #include <linux/sunrpc/clnt.h>
 #include <linux/sunrpc/svc.h>
 #include <linux/nfsd/nfsd.h>

 #define NFSDDBG_FACILITY		NFSDDBG_FH


 static int nfsd_nr_verified;
 static int nfsd_nr_put;

 extern struct export_operations export_op_default;

 #define	CALL(ops,fun) ((ops->fun)?(ops->fun):export_op_default.fun)

 /*
  * 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_dentry && ! IS_ROOT(tdentry)) {
 		/* make sure parents give x permission to user */
 		int err;
 		parent = dget_parent(tdentry);
 		err = permission(parent->d_inode, MAY_EXEC, NULL);
 		if (err < 0) {
 			dput(parent);
 			break;
 		}
 		dput(tdentry);
 		tdentry = parent;
 	}
 	if (tdentry != exp->ex_dentry)
 		dprintk("nfsd_acceptable failed at %p %s\n", tdentry, tdentry->d_name.name);
 	rv = (tdentry == exp->ex_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, int type)
 {
 	/* Type can be negative when creating hardlinks - not to a dir */
 	if (type > 0 && (mode & S_IFMT) != type) {
 		if (rqstp->rq_vers == 4 && (mode & S_IFMT) == S_IFLNK)
 			return nfserr_symlink;
 		else if (type == S_IFDIR)
 			return nfserr_notdir;
 		else if ((mode & S_IFMT) == S_IFDIR)
 			return nfserr_isdir;
 		else
 			return nfserr_inval;
 	}
 	if (type < 0 && (mode & S_IFMT) == -type) {
 		if (rqstp->rq_vers == 4 && (mode & S_IFMT) == S_IFLNK)
 			return nfserr_symlink;
 		else if (type == -S_IFDIR)
 			return nfserr_isdir;
 		else
 			return nfserr_notdir;
 	}
 	return 0;
 }

 /*
  * Perform sanity checks on the dentry in a client's file handle.
  *
  * Note that the file handle dentry may need to be freed even after
  * an error return.
  *
  * This is only called at the start of an nfsproc call, so fhp points to
  * a svc_fh which is all 0 except for the over-the-wire file handle.
  */
 __be32
 fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, int type, int access)
 {
 	struct knfsd_fh	*fh = &fhp->fh_handle;
 	struct svc_export *exp = NULL;
 	struct dentry	*dentry;
 	__be32		error = 0;

 	dprintk("nfsd: fh_verify(%s)\n", SVCFH_fmt(fhp));

 	if (!fhp->fh_dentry) {
 		__u32 *datap=NULL;
 		__u32 tfh[3];		/* filehandle fragment for oldstyle filehandles */
 		int fileid_type;
 		int data_left = fh->fh_size/4;

 		error = nfserr_stale;
 		if (rqstp->rq_client == NULL)
 			goto out;
 		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;
 			datap = fh->fh_auth;
 			if (--data_left<0) goto out;
 			switch (fh->fh_auth_type) {
 			case 0: break;
 			default: goto out;
 			}
 			len = key_len(fh->fh_fsid_type) / 4;
 			if (len == 0) goto out;
 			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;
 				fh->fh_fsid[0] = new_encode_dev(MKDEV(ntohl(fh->fh_fsid[0]), ntohl(fh->fh_fsid[1])));
 				fh->fh_fsid[1] = fh->fh_fsid[2];
 			}
 			if ((data_left -= len)<0) goto out;
 			exp = exp_find(rqstp->rq_client, fh->fh_fsid_type, datap, &rqstp->rq_chandle);
 			datap += len;
 		} else {
 			dev_t xdev;
 			ino_t xino;
 			if (fh->fh_size != NFS_FHSIZE)
 				goto out;
 			/* 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 = exp_find(rqstp->rq_client, FSID_DEV, tfh,
 				       &rqstp->rq_chandle);
 		}

 		if (IS_ERR(exp) && (PTR_ERR(exp) == -EAGAIN
 				|| PTR_ERR(exp) == -ETIMEDOUT)) {
 			error = nfserrno(PTR_ERR(exp));
 			goto out;
 		}

 		error = nfserr_stale;
 		if (!exp || IS_ERR(exp))
 			goto out;

 		/* Check if the request originated from a secure port. */
 		error = nfserr_perm;
 		if (!rqstp->rq_secure && EX_SECURE(exp)) {
 			char buf[RPC_MAX_ADDRBUFLEN];
 			printk(KERN_WARNING
 			       "nfsd: request from insecure port %s!\n",
 			       svc_print_addr(rqstp, buf, sizeof(buf)));
 			goto out;
 		}

 		/* Set user creds for this exportpoint */
 		error = nfserrno(nfsd_setuser(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) {
 			tfh[0] = fh->ofh_ino;
 			tfh[1] = fh->ofh_generation;
 			tfh[2] = fh->ofh_dirino;
 			datap = tfh;
 			data_left = 3;
 			if (fh->ofh_dirino == 0)
 				fileid_type = 1;
 			else
 				fileid_type = 2;
 		} else
 			fileid_type = fh->fh_fileid_type;

 		if (fileid_type == 0)
 			dentry = dget(exp->ex_dentry);
 		else {
 			struct export_operations *nop = exp->ex_mnt->mnt_sb->s_export_op;
 			dentry = CALL(nop,decode_fh)(exp->ex_mnt->mnt_sb,
 						     datap, 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 (S_ISDIR(dentry->d_inode->i_mode) &&
 		    (dentry->d_flags & DCACHE_DISCONNECTED)) {
 			printk("nfsd: find_fh_dentry returned a DISCONNECTED directory: %s/%s\n",
 			       dentry->d_parent->d_name.name, dentry->d_name.name);
 		}

 		fhp->fh_dentry = dentry;
 		fhp->fh_export = exp;
 		nfsd_nr_verified++;
 	} else {
 		/* just rechecking permissions
 		 * (e.g. nfsproc_create calls fh_verify, then nfsd_create does as well)
 		 */
 		dprintk("nfsd: fh_verify - just checking\n");
 		dentry = fhp->fh_dentry;
 		exp = fhp->fh_export;
 		/* Set user creds for this exportpoint; necessary even
 		 * in the "just checking" case because this may be a
 		 * filehandle that was created by fh_compose, and that
 		 * is about to be used in another nfsv4 compound
 		 * operation */
 		error = nfserrno(nfsd_setuser(rqstp, exp));
 		if (error)
 			goto out;
 	}
 	cache_get(&exp->h);


 	error = nfsd_mode_check(rqstp, dentry->d_inode->i_mode, type);
 	if (error)
 		goto out;

 	/* Finally, check access permissions. */
 	error = nfsd_permission(exp, dentry, access);

 	if (error) {
 		dprintk("fh_verify: %s/%s permission failure, "
 			"acc=%x, error=%d\n",
 			dentry->d_parent->d_name.name,
 			dentry->d_name.name,
 			access, ntohl(error));
 	}
 out:
 	if (exp && !IS_ERR(exp))
 		exp_put(exp);
 	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 inline int _fh_update(struct dentry *dentry, struct svc_export *exp,
 			     __u32 *datap, int *maxsize)
 {
 	struct export_operations *nop = exp->ex_mnt->mnt_sb->s_export_op;

 	if (dentry == exp->ex_dentry) {
 		*maxsize = 0;
 		return 0;
 	}

 	return CALL(nop,encode_fh)(dentry, datap, maxsize,
 			  !(exp->ex_flags&NFSEXP_NOSUBTREECHECK));
 }

 /*
  * 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(dentry->d_inode->i_ino);
 	fh->ofh_generation = dentry->d_inode->i_generation;
 	if (S_ISDIR(dentry->d_inode->i_mode) ||
 	    (exp->ex_flags & NFSEXP_NOSUBTREECHECK))
 		fh->ofh_dirino = 0;
 }

 __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
 	 *
 	 */

 	u8 version;
 	u8 fsid_type = 0;
 	struct inode * inode = dentry->d_inode;
 	struct dentry *parent = dentry->d_parent;
 	__u32 *datap;
 	dev_t ex_dev = exp->ex_dentry->d_inode->i_sb->s_dev;
 	int root_export = (exp->ex_dentry == exp->ex_dentry->d_sb->s_root);

 	dprintk("nfsd: fh_compose(exp %02x:%02x/%ld %s/%s, ino=%ld)\n",
 		MAJOR(ex_dev), MINOR(ex_dev),
 		(long) exp->ex_dentry->d_inode->i_ino,
 		parent->d_name.name, dentry->d_name.name,
 		(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.
 	 */
  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;

 		if (ref_fh == fhp)
 			fh_put(ref_fh);
 		ref_fh = NULL;

 		switch (version) {
 		case 0xca:
 			fsid_type = FSID_DEV;
 			break;
 		case 1:
 			break;
 		default:
 			goto retry;
 		}

 		/* Need to check that this type works for this
 		 * export point.  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.
 		 */
 		switch(fsid_type) {
 		case FSID_DEV:
 			if (!old_valid_dev(ex_dev))
 				goto retry;
 			/* FALL THROUGH */
 		case FSID_MAJOR_MINOR:
 		case FSID_ENCODE_DEV:
 			if (!(exp->ex_dentry->d_inode->i_sb->s_type->fs_flags
 			      & FS_REQUIRES_DEV))
 				goto retry;
 			break;
 		case FSID_NUM:
 			if (! (exp->ex_flags & NFSEXP_FSID))
 				goto retry;
 			break;
 		case FSID_UUID8:
 		case FSID_UUID16:
 			if (!root_export)
 				goto retry;
 			/* fall through */
 		case FSID_UUID4_INUM:
 		case FSID_UUID16_INUM:
 			if (exp->ex_uuid == NULL)
 				goto retry;
 			break;
 		}
 	} else if (exp->ex_uuid) {
 		if (fhp->fh_maxsize >= 64) {
 			if (root_export)
 				fsid_type = FSID_UUID16;
 			else
 				fsid_type = FSID_UUID16_INUM;
 		} else {
 			if (root_export)
 				fsid_type = FSID_UUID8;
 			else
 				fsid_type = FSID_UUID4_INUM;
 		}
 	} else if (exp->ex_flags & NFSEXP_FSID)
 		fsid_type = FSID_NUM;
 	else if (!old_valid_dev(ex_dev))
 		/* for newer device numbers, we must use a newer fsid format */
 		fsid_type = FSID_ENCODE_DEV;
 	else
 		fsid_type = FSID_DEV;

 	if (ref_fh == fhp)
 		fh_put(ref_fh);

 	if (fhp->fh_locked || fhp->fh_dentry) {
 		printk(KERN_ERR "fh_compose: fh %s/%s not initialized!\n",
 		       parent->d_name.name, dentry->d_name.name);
 	}
 	if (fhp->fh_maxsize < NFS_FHSIZE)
 		printk(KERN_ERR "fh_compose: called with maxsize %d! %s/%s\n",
 		       fhp->fh_maxsize,
 		       parent->d_name.name, dentry->d_name.name);

 	fhp->fh_dentry = dget(dentry); /* our internal copy */
 	fhp->fh_export = exp;
 	cache_get(&exp->h);

 	if (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(exp->ex_dentry->d_inode->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 {
 		int len;
 		fhp->fh_handle.fh_version = 1;
 		fhp->fh_handle.fh_auth_type = 0;
 		datap = fhp->fh_handle.fh_auth+0;
 		fhp->fh_handle.fh_fsid_type = fsid_type;
 		mk_fsid(fsid_type, datap, ex_dev,
 			exp->ex_dentry->d_inode->i_ino,
 			exp->ex_fsid, exp->ex_uuid);

 		len = key_len(fsid_type);
 		datap += len/4;
 		fhp->fh_handle.fh_size = 4 + len;

 		if (inode) {
 			int size = (fhp->fh_maxsize-len-4)/4;
 			fhp->fh_handle.fh_fileid_type =
 				_fh_update(dentry, exp, datap, &size);
 			fhp->fh_handle.fh_size += size*4;
 		}
 		if (fhp->fh_handle.fh_fileid_type == 255)
 			return nfserr_opnotsupp;
 	}

 	nfsd_nr_verified++;
 	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;
 	__u32 *datap;

 	if (!fhp->fh_dentry)
 		goto out_bad;

 	dentry = fhp->fh_dentry;
 	if (!dentry->d_inode)
 		goto out_negative;
 	if (fhp->fh_handle.fh_version != 1) {
 		_fh_update_old(dentry, fhp->fh_export, &fhp->fh_handle);
 	} else {
 		int size;
 		if (fhp->fh_handle.fh_fileid_type != 0)
 			goto out;
 		datap = fhp->fh_handle.fh_auth+
 			fhp->fh_handle.fh_size/4 -1;
 		size = (fhp->fh_maxsize - fhp->fh_handle.fh_size)/4;
 		fhp->fh_handle.fh_fileid_type =
 			_fh_update(dentry, fhp->fh_export, datap, &size);
 		fhp->fh_handle.fh_size += size*4;
 		if (fhp->fh_handle.fh_fileid_type == 255)
 			return nfserr_opnotsupp;
 	}
 out:
 	return 0;

 out_bad:
 	printk(KERN_ERR "fh_update: fh not verified!\n");
 	goto out;
 out_negative:
 	printk(KERN_ERR "fh_update: %s/%s still negative!\n",
 		dentry->d_parent->d_name.name, dentry->d_name.name);
 	goto out;
 }

 /*
  * 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
 		nfsd_nr_put++;
 	}
 	if (exp) {
 		cache_put(&exp->h, &svc_export_cache);
 		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:
 		return FSIDSOURCE_DEV;
 	case FSID_NUM:
 		return FSIDSOURCE_FSID;
 	default:
 		if (fhp->fh_export->ex_flags & NFSEXP_FSID)
 			return FSIDSOURCE_FSID;
 		else
 			return FSIDSOURCE_UUID;
 	}
 }
	/*
	* linux/fs/nfsd/nfsfh.c
	*
	* 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/slab.h>
	#include <linux/fs.h>
	#include <linux/unistd.h>
	#include <linux/string.h>
	#include <linux/stat.h>
	#include <linux/dcache.h>
	#include <linux/mount.h>

	#include <linux/sunrpc/clnt.h>
	#include <linux/sunrpc/svc.h>
	#include <linux/nfsd/nfsd.h>

	#define NFSDDBG_FACILITY NFSDDBG_FH


	static int nfsd_nr_verified;
	static int nfsd_nr_put;

	extern struct export_operations export_op_default;

	#define CALL(ops,fun) ((ops->fun)?(ops->fun):export_op_default.fun)

	/*
	* 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_dentry && ! IS_ROOT(tdentry)) {
	/* make sure parents give x permission to user */
	int err;
	parent = dget_parent(tdentry);
	err = permission(parent->d_inode, MAY_EXEC, NULL);
	if (err < 0) {
	dput(parent);
	break;
	}
	dput(tdentry);
	tdentry = parent;
	}
	if (tdentry != exp->ex_dentry)
	dprintk("nfsd_acceptable failed at %p %s\n", tdentry, tdentry->d_name.name);
	rv = (tdentry == exp->ex_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, int type)
	{
	/* Type can be negative when creating hardlinks - not to a dir */
	if (type > 0 && (mode & S_IFMT) != type) {
	if (rqstp->rq_vers == 4 && (mode & S_IFMT) == S_IFLNK)
	return nfserr_symlink;
	else if (type == S_IFDIR)
	return nfserr_notdir;
	else if ((mode & S_IFMT) == S_IFDIR)
	return nfserr_isdir;
	else
	return nfserr_inval;
	}
	if (type < 0 && (mode & S_IFMT) == -type) {
	if (rqstp->rq_vers == 4 && (mode & S_IFMT) == S_IFLNK)
	return nfserr_symlink;
	else if (type == -S_IFDIR)
	return nfserr_isdir;
	else
	return nfserr_notdir;
	}
	return 0;
	}

	/*
	* Perform sanity checks on the dentry in a client's file handle.
	*
	* Note that the file handle dentry may need to be freed even after
	* an error return.
	*
	* This is only called at the start of an nfsproc call, so fhp points to
	* a svc_fh which is all 0 except for the over-the-wire file handle.
	*/
	__be32
	fh_verify(struct svc_rqst rqstp, struct svc_fh fhp, int type, int access)
	{
	struct knfsd_fh *fh = &fhp->fh_handle;
	struct svc_export *exp = NULL;
	struct dentry *dentry;
	__be32 error = 0;

	dprintk("nfsd: fh_verify(%s)\n", SVCFH_fmt(fhp));

	if (!fhp->fh_dentry) {
	__u32 *datap=NULL;
	__u32 tfh[3]; /* filehandle fragment for oldstyle filehandles */
	int fileid_type;
	int data_left = fh->fh_size/4;

	error = nfserr_stale;
	if (rqstp->rq_client == NULL)
	goto out;
	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;
	datap = fh->fh_auth;
	if (--data_left<0) goto out;
	switch (fh->fh_auth_type) {
	case 0: break;
	default: goto out;
	}
	len = key_len(fh->fh_fsid_type) / 4;
	if (len == 0) goto out;
	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;
	fh->fh_fsid[0] = new_encode_dev(MKDEV(ntohl(fh->fh_fsid[0]), ntohl(fh->fh_fsid[1])));
	fh->fh_fsid[1] = fh->fh_fsid[2];
	}
	if ((data_left -= len)<0) goto out;
	exp = exp_find(rqstp->rq_client, fh->fh_fsid_type, datap, &rqstp->rq_chandle);
	datap += len;
	} else {
	dev_t xdev;
	ino_t xino;
	if (fh->fh_size != NFS_FHSIZE)
	goto out;
	/* 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 = exp_find(rqstp->rq_client, FSID_DEV, tfh,
	&rqstp->rq_chandle);
	}

	if (IS_ERR(exp) && (PTR_ERR(exp) == -EAGAIN
	\|\| PTR_ERR(exp) == -ETIMEDOUT)) {
	error = nfserrno(PTR_ERR(exp));
	goto out;
	}

	error = nfserr_stale;
	if (!exp \|\| IS_ERR(exp))
	goto out;

	/* Check if the request originated from a secure port. */
	error = nfserr_perm;
	if (!rqstp->rq_secure && EX_SECURE(exp)) {
	char buf[RPC_MAX_ADDRBUFLEN];
	printk(KERN_WARNING
	"nfsd: request from insecure port %s!\n",
	svc_print_addr(rqstp, buf, sizeof(buf)));
	goto out;
	}

	/* Set user creds for this exportpoint */
	error = nfserrno(nfsd_setuser(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) {
	tfh[0] = fh->ofh_ino;
	tfh[1] = fh->ofh_generation;
	tfh[2] = fh->ofh_dirino;
	datap = tfh;
	data_left = 3;
	if (fh->ofh_dirino == 0)
	fileid_type = 1;
	else
	fileid_type = 2;
	} else
	fileid_type = fh->fh_fileid_type;

	if (fileid_type == 0)
	dentry = dget(exp->ex_dentry);
	else {
	struct export_operations *nop = exp->ex_mnt->mnt_sb->s_export_op;
	dentry = CALL(nop,decode_fh)(exp->ex_mnt->mnt_sb,
	datap, 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 (S_ISDIR(dentry->d_inode->i_mode) &&
	(dentry->d_flags & DCACHE_DISCONNECTED)) {
	printk("nfsd: find_fh_dentry returned a DISCONNECTED directory: %s/%s\n",
	dentry->d_parent->d_name.name, dentry->d_name.name);
	}

	fhp->fh_dentry = dentry;
	fhp->fh_export = exp;
	nfsd_nr_verified++;
	} else {
	/* just rechecking permissions
	* (e.g. nfsproc_create calls fh_verify, then nfsd_create does as well)
	*/
	dprintk("nfsd: fh_verify - just checking\n");
	dentry = fhp->fh_dentry;
	exp = fhp->fh_export;
	/* Set user creds for this exportpoint; necessary even
	* in the "just checking" case because this may be a
	* filehandle that was created by fh_compose, and that
	* is about to be used in another nfsv4 compound
	* operation */
	error = nfserrno(nfsd_setuser(rqstp, exp));
	if (error)
	goto out;
	}
	cache_get(&exp->h);


	error = nfsd_mode_check(rqstp, dentry->d_inode->i_mode, type);
	if (error)
	goto out;

	/* Finally, check access permissions. */
	error = nfsd_permission(exp, dentry, access);

	if (error) {
	dprintk("fh_verify: %s/%s permission failure, "
	"acc=%x, error=%d\n",
	dentry->d_parent->d_name.name,
	dentry->d_name.name,
	access, ntohl(error));
	}
	out:
	if (exp && !IS_ERR(exp))
	exp_put(exp);
	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 inline int _fh_update(struct dentry dentry, struct svc_export exp,
	__u32 datap, int maxsize)
	{
	struct export_operations *nop = exp->ex_mnt->mnt_sb->s_export_op;

	if (dentry == exp->ex_dentry) {
	*maxsize = 0;
	return 0;
	}

	return CALL(nop,encode_fh)(dentry, datap, maxsize,
	!(exp->ex_flags&NFSEXP_NOSUBTREECHECK));
	}

	/*
	* 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(dentry->d_inode->i_ino);
	fh->ofh_generation = dentry->d_inode->i_generation;
	if (S_ISDIR(dentry->d_inode->i_mode) \|\|
	(exp->ex_flags & NFSEXP_NOSUBTREECHECK))
	fh->ofh_dirino = 0;
	}

	__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
	*
	*/

	u8 version;
	u8 fsid_type = 0;
	struct inode * inode = dentry->d_inode;
	struct dentry *parent = dentry->d_parent;
	__u32 *datap;
	dev_t ex_dev = exp->ex_dentry->d_inode->i_sb->s_dev;
	int root_export = (exp->ex_dentry == exp->ex_dentry->d_sb->s_root);

	dprintk("nfsd: fh_compose(exp %02x:%02x/%ld %s/%s, ino=%ld)\n",
	MAJOR(ex_dev), MINOR(ex_dev),
	(long) exp->ex_dentry->d_inode->i_ino,
	parent->d_name.name, dentry->d_name.name,
	(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.
	*/
	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;

	if (ref_fh == fhp)
	fh_put(ref_fh);
	ref_fh = NULL;

	switch (version) {
	case 0xca:
	fsid_type = FSID_DEV;
	break;
	case 1:
	break;
	default:
	goto retry;
	}

	/* Need to check that this type works for this
	* export point. 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.
	*/
	switch(fsid_type) {
	case FSID_DEV:
	if (!old_valid_dev(ex_dev))
	goto retry;
	/* FALL THROUGH */
	case FSID_MAJOR_MINOR:
	case FSID_ENCODE_DEV:
	if (!(exp->ex_dentry->d_inode->i_sb->s_type->fs_flags
	& FS_REQUIRES_DEV))
	goto retry;
	break;
	case FSID_NUM:
	if (! (exp->ex_flags & NFSEXP_FSID))
	goto retry;
	break;
	case FSID_UUID8:
	case FSID_UUID16:
	if (!root_export)
	goto retry;
	/* fall through */
	case FSID_UUID4_INUM:
	case FSID_UUID16_INUM:
	if (exp->ex_uuid == NULL)
	goto retry;
	break;
	}
	} else if (exp->ex_uuid) {
	if (fhp->fh_maxsize >= 64) {
	if (root_export)
	fsid_type = FSID_UUID16;
	else
	fsid_type = FSID_UUID16_INUM;
	} else {
	if (root_export)
	fsid_type = FSID_UUID8;
	else
	fsid_type = FSID_UUID4_INUM;
	}
	} else if (exp->ex_flags & NFSEXP_FSID)
	fsid_type = FSID_NUM;
	else if (!old_valid_dev(ex_dev))
	/* for newer device numbers, we must use a newer fsid format */
	fsid_type = FSID_ENCODE_DEV;
	else
	fsid_type = FSID_DEV;

	if (ref_fh == fhp)
	fh_put(ref_fh);

	if (fhp->fh_locked \|\| fhp->fh_dentry) {
	printk(KERN_ERR "fh_compose: fh %s/%s not initialized!\n",
	parent->d_name.name, dentry->d_name.name);
	}
	if (fhp->fh_maxsize < NFS_FHSIZE)
	printk(KERN_ERR "fh_compose: called with maxsize %d! %s/%s\n",
	fhp->fh_maxsize,
	parent->d_name.name, dentry->d_name.name);

	fhp->fh_dentry = dget(dentry); /* our internal copy */
	fhp->fh_export = exp;
	cache_get(&exp->h);

	if (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(exp->ex_dentry->d_inode->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 {
	int len;
	fhp->fh_handle.fh_version = 1;
	fhp->fh_handle.fh_auth_type = 0;
	datap = fhp->fh_handle.fh_auth+0;
	fhp->fh_handle.fh_fsid_type = fsid_type;
	mk_fsid(fsid_type, datap, ex_dev,
	exp->ex_dentry->d_inode->i_ino,
	exp->ex_fsid, exp->ex_uuid);

	len = key_len(fsid_type);
	datap += len/4;
	fhp->fh_handle.fh_size = 4 + len;

	if (inode) {
	int size = (fhp->fh_maxsize-len-4)/4;
	fhp->fh_handle.fh_fileid_type =
	_fh_update(dentry, exp, datap, &size);
	fhp->fh_handle.fh_size += size*4;
	}
	if (fhp->fh_handle.fh_fileid_type == 255)
	return nfserr_opnotsupp;
	}

	nfsd_nr_verified++;
	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;
	__u32 *datap;

	if (!fhp->fh_dentry)
	goto out_bad;

	dentry = fhp->fh_dentry;
	if (!dentry->d_inode)
	goto out_negative;
	if (fhp->fh_handle.fh_version != 1) {
	_fh_update_old(dentry, fhp->fh_export, &fhp->fh_handle);
	} else {
	int size;
	if (fhp->fh_handle.fh_fileid_type != 0)
	goto out;
	datap = fhp->fh_handle.fh_auth+
	fhp->fh_handle.fh_size/4 -1;
	size = (fhp->fh_maxsize - fhp->fh_handle.fh_size)/4;
	fhp->fh_handle.fh_fileid_type =
	_fh_update(dentry, fhp->fh_export, datap, &size);
	fhp->fh_handle.fh_size += size*4;
	if (fhp->fh_handle.fh_fileid_type == 255)
	return nfserr_opnotsupp;
	}
	out:
	return 0;

	out_bad:
	printk(KERN_ERR "fh_update: fh not verified!\n");
	goto out;
	out_negative:
	printk(KERN_ERR "fh_update: %s/%s still negative!\n",
	dentry->d_parent->d_name.name, dentry->d_name.name);
	goto out;
	}

	/*
	* 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
	nfsd_nr_put++;
	}
	if (exp) {
	cache_put(&exp->h, &svc_export_cache);
	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:
	return FSIDSOURCE_DEV;
	case FSID_NUM:
	return FSIDSOURCE_FSID;
	default:
	if (fhp->fh_export->ex_flags & NFSEXP_FSID)
	return FSIDSOURCE_FSID;
	else
	return FSIDSOURCE_UUID;
	}
	}