// SPDX-License-Identifier: GPL-2.0

  /*
   * linux/fs/nfs/nfs2xdr.c
   *
   * XDR functions to encode/decode NFS RPC arguments and results.
   *
   * Copyright (C) 1992, 1993, 1994  Rick Sladkey
   * Copyright (C) 1996 Olaf Kirch
   * 04 Aug 1998  Ion Badulescu <ionut@cs.columbia.edu>
   * 		FIFO's need special handling in NFSv2
   */
  
  #include <linux/param.h>
  #include <linux/time.h>
  #include <linux/mm.h>

  #include <linux/errno.h>
  #include <linux/string.h>
  #include <linux/in.h>
  #include <linux/pagemap.h>
  #include <linux/proc_fs.h>
  #include <linux/sunrpc/clnt.h>
  #include <linux/nfs.h>
  #include <linux/nfs2.h>
  #include <linux/nfs_fs.h>

  #include "internal.h"

  
  #define NFSDBG_FACILITY		NFSDBG_XDR

  /* Mapping from NFS error code to "errno" error code. */
  #define errno_NFSERR_IO		EIO
  
  /*
   * Declare the space requirements for NFS arguments and replies as
   * number of 32bit-words
   */
  #define NFS_fhandle_sz		(8)
  #define NFS_sattr_sz		(8)
  #define NFS_filename_sz		(1+(NFS2_MAXNAMLEN>>2))
  #define NFS_path_sz		(1+(NFS2_MAXPATHLEN>>2))
  #define NFS_fattr_sz		(17)
  #define NFS_info_sz		(5)
  #define NFS_entry_sz		(NFS_filename_sz+3)
  
  #define NFS_diropargs_sz	(NFS_fhandle_sz+NFS_filename_sz)

  #define NFS_removeargs_sz	(NFS_fhandle_sz+NFS_filename_sz)

  #define NFS_sattrargs_sz	(NFS_fhandle_sz+NFS_sattr_sz)
  #define NFS_readlinkargs_sz	(NFS_fhandle_sz)
  #define NFS_readargs_sz		(NFS_fhandle_sz+3)
  #define NFS_writeargs_sz	(NFS_fhandle_sz+4)
  #define NFS_createargs_sz	(NFS_diropargs_sz+NFS_sattr_sz)
  #define NFS_renameargs_sz	(NFS_diropargs_sz+NFS_diropargs_sz)
  #define NFS_linkargs_sz		(NFS_fhandle_sz+NFS_diropargs_sz)

  #define NFS_symlinkargs_sz	(NFS_diropargs_sz+1+NFS_sattr_sz)

  #define NFS_readdirargs_sz	(NFS_fhandle_sz+2)
  
  #define NFS_attrstat_sz		(1+NFS_fattr_sz)
  #define NFS_diropres_sz		(1+NFS_fhandle_sz+NFS_fattr_sz)
  #define NFS_readlinkres_sz	(2)
  #define NFS_readres_sz		(1+NFS_fattr_sz+1)
  #define NFS_writeres_sz         (NFS_attrstat_sz)
  #define NFS_stat_sz		(1)
  #define NFS_readdirres_sz	(1)
  #define NFS_statfsres_sz	(1+NFS_info_sz)

  static int nfs_stat_to_errno(enum nfs_stat);

  
  /*
   * While encoding arguments, set up the reply buffer in advance to
   * receive reply data directly into the page cache.
   */
  static void prepare_reply_buffer(struct rpc_rqst *req, struct page **pages,
  				 unsigned int base, unsigned int len,
  				 unsigned int bufsize)
  {
  	struct rpc_auth	*auth = req->rq_cred->cr_auth;
  	unsigned int replen;
  
  	replen = RPC_REPHDRSIZE + auth->au_rslack + bufsize;
  	xdr_inline_pages(&req->rq_rcv_buf, replen << 2, pages, base, len);
  }

  /*
   * Handle decode buffer overflows out-of-line.
   */
  static void print_overflow_msg(const char *func, const struct xdr_stream *xdr)
  {
  	dprintk("NFS: %s prematurely hit the end of our receive buffer. "
  		"Remaining buffer length is %tu words.
  ",
  		func, xdr->end - xdr->p);
  }

  /*

   * Encode/decode NFSv2 basic data types
   *
   * Basic NFSv2 data types are defined in section 2.3 of RFC 1094:
   * "NFS: Network File System Protocol Specification".
   *
   * Not all basic data types have their own encoding and decoding
   * functions.  For run-time efficiency, some data types are encoded
   * or decoded inline.
   */
  
  /*

   *	typedef opaque	nfsdata<>;
   */

  static int decode_nfsdata(struct xdr_stream *xdr, struct nfs_pgio_res *result)

  {
  	u32 recvd, count;

  	__be32 *p;
  
  	p = xdr_inline_decode(xdr, 4);
  	if (unlikely(p == NULL))
  		goto out_overflow;
  	count = be32_to_cpup(p);

  	recvd = xdr_read_pages(xdr, count);

  	if (unlikely(count > recvd))
  		goto out_cheating;
  out:

  	result->eof = 0;	/* NFSv2 does not pass EOF flag on the wire. */
  	result->count = count;
  	return count;
  out_cheating:
  	dprintk("NFS: server cheating in read result: "
  		"count %u > recvd %u
  ", count, recvd);
  	count = recvd;
  	goto out;
  out_overflow:
  	print_overflow_msg(__func__, xdr);
  	return -EIO;
  }
  
  /*
   *	enum stat {
   *		NFS_OK = 0,
   *		NFSERR_PERM = 1,
   *		NFSERR_NOENT = 2,
   *		NFSERR_IO = 5,
   *		NFSERR_NXIO = 6,
   *		NFSERR_ACCES = 13,
   *		NFSERR_EXIST = 17,
   *		NFSERR_NODEV = 19,
   *		NFSERR_NOTDIR = 20,
   *		NFSERR_ISDIR = 21,
   *		NFSERR_FBIG = 27,
   *		NFSERR_NOSPC = 28,
   *		NFSERR_ROFS = 30,
   *		NFSERR_NAMETOOLONG = 63,
   *		NFSERR_NOTEMPTY = 66,
   *		NFSERR_DQUOT = 69,
   *		NFSERR_STALE = 70,
   *		NFSERR_WFLUSH = 99
   *	};
   */
  static int decode_stat(struct xdr_stream *xdr, enum nfs_stat *status)
  {
  	__be32 *p;
  
  	p = xdr_inline_decode(xdr, 4);
  	if (unlikely(p == NULL))
  		goto out_overflow;
  	*status = be32_to_cpup(p);
  	return 0;
  out_overflow:
  	print_overflow_msg(__func__, xdr);
  	return -EIO;
  }
  
  /*

   * 2.3.2.  ftype
   *
   *	enum ftype {
   *		NFNON = 0,
   *		NFREG = 1,
   *		NFDIR = 2,
   *		NFBLK = 3,
   *		NFCHR = 4,
   *		NFLNK = 5
   *	};
   *
   */
  static __be32 *xdr_decode_ftype(__be32 *p, u32 *type)
  {
  	*type = be32_to_cpup(p++);
  	if (unlikely(*type > NF2FIFO))
  		*type = NFBAD;
  	return p;
  }
  
  /*

   * 2.3.3.  fhandle
   *
   *	typedef opaque fhandle[FHSIZE];
   */
  static void encode_fhandle(struct xdr_stream *xdr, const struct nfs_fh *fh)
  {
  	__be32 *p;

  	p = xdr_reserve_space(xdr, NFS2_FHSIZE);
  	memcpy(p, fh->data, NFS2_FHSIZE);
  }

  static int decode_fhandle(struct xdr_stream *xdr, struct nfs_fh *fh)
  {
  	__be32 *p;
  
  	p = xdr_inline_decode(xdr, NFS2_FHSIZE);
  	if (unlikely(p == NULL))
  		goto out_overflow;
  	fh->size = NFS2_FHSIZE;
  	memcpy(fh->data, p, NFS2_FHSIZE);
  	return 0;
  out_overflow:
  	print_overflow_msg(__func__, xdr);
  	return -EIO;
  }

  /*

   * 2.3.4.  timeval
   *
   *	struct timeval {
   *		unsigned int seconds;
   *		unsigned int useconds;
   *	};
   */
  static __be32 *xdr_encode_time(__be32 *p, const struct timespec *timep)
  {
  	*p++ = cpu_to_be32(timep->tv_sec);
  	if (timep->tv_nsec != 0)
  		*p++ = cpu_to_be32(timep->tv_nsec / NSEC_PER_USEC);
  	else
  		*p++ = cpu_to_be32(0);
  	return p;
  }
  
  /*
   * Passing the invalid value useconds=1000000 is a Sun convention for
   * "set to current server time".  It's needed to make permissions checks
   * for the "touch" program across v2 mounts to Solaris and Irix servers
   * work correctly.  See description of sattr in section 6.1 of "NFS
   * Illustrated" by Brent Callaghan, Addison-Wesley, ISBN 0-201-32750-5.
   */
  static __be32 *xdr_encode_current_server_time(__be32 *p,
  					      const struct timespec *timep)
  {
  	*p++ = cpu_to_be32(timep->tv_sec);
  	*p++ = cpu_to_be32(1000000);
  	return p;
  }

  static __be32 *xdr_decode_time(__be32 *p, struct timespec *timep)
  {
  	timep->tv_sec = be32_to_cpup(p++);
  	timep->tv_nsec = be32_to_cpup(p++) * NSEC_PER_USEC;
  	return p;
  }

  /*

   * 2.3.5.  fattr
   *
   *	struct fattr {
   *		ftype		type;
   *		unsigned int	mode;
   *		unsigned int	nlink;
   *		unsigned int	uid;
   *		unsigned int	gid;
   *		unsigned int	size;
   *		unsigned int	blocksize;
   *		unsigned int	rdev;
   *		unsigned int	blocks;
   *		unsigned int	fsid;
   *		unsigned int	fileid;
   *		timeval		atime;
   *		timeval		mtime;
   *		timeval		ctime;
   *	};
   *
   */
  static int decode_fattr(struct xdr_stream *xdr, struct nfs_fattr *fattr)
  {

  	u32 rdev, type;

  	__be32 *p;
  
  	p = xdr_inline_decode(xdr, NFS_fattr_sz << 2);
  	if (unlikely(p == NULL))
  		goto out_overflow;

  
  	fattr->valid |= NFS_ATTR_FATTR_V2;
  
  	p = xdr_decode_ftype(p, &type);
  
  	fattr->mode = be32_to_cpup(p++);
  	fattr->nlink = be32_to_cpup(p++);

  	fattr->uid = make_kuid(&init_user_ns, be32_to_cpup(p++));
  	if (!uid_valid(fattr->uid))
  		goto out_uid;
  	fattr->gid = make_kgid(&init_user_ns, be32_to_cpup(p++));
  	if (!gid_valid(fattr->gid))
  		goto out_gid;
  		

  	fattr->size = be32_to_cpup(p++);
  	fattr->du.nfs2.blocksize = be32_to_cpup(p++);
  
  	rdev = be32_to_cpup(p++);
  	fattr->rdev = new_decode_dev(rdev);
  	if (type == (u32)NFCHR && rdev == (u32)NFS2_FIFO_DEV) {
  		fattr->mode = (fattr->mode & ~S_IFMT) | S_IFIFO;
  		fattr->rdev = 0;
  	}
  
  	fattr->du.nfs2.blocks = be32_to_cpup(p++);
  	fattr->fsid.major = be32_to_cpup(p++);
  	fattr->fsid.minor = 0;
  	fattr->fileid = be32_to_cpup(p++);
  
  	p = xdr_decode_time(p, &fattr->atime);
  	p = xdr_decode_time(p, &fattr->mtime);
  	xdr_decode_time(p, &fattr->ctime);

  	fattr->change_attr = nfs_timespec_to_change_attr(&fattr->ctime);

  	return 0;

  out_uid:
  	dprintk("NFS: returned invalid uid
  ");
  	return -EINVAL;
  out_gid:
  	dprintk("NFS: returned invalid gid
  ");
  	return -EINVAL;

  out_overflow:
  	print_overflow_msg(__func__, xdr);
  	return -EIO;
  }
  
  /*

   * 2.3.6.  sattr
   *
   *	struct sattr {
   *		unsigned int	mode;
   *		unsigned int	uid;
   *		unsigned int	gid;
   *		unsigned int	size;
   *		timeval		atime;
   *		timeval		mtime;
   *	};
   */
  
  #define NFS2_SATTR_NOT_SET	(0xffffffff)
  
  static __be32 *xdr_time_not_set(__be32 *p)
  {
  	*p++ = cpu_to_be32(NFS2_SATTR_NOT_SET);
  	*p++ = cpu_to_be32(NFS2_SATTR_NOT_SET);
  	return p;
  }
  
  static void encode_sattr(struct xdr_stream *xdr, const struct iattr *attr)
  {
  	__be32 *p;
  
  	p = xdr_reserve_space(xdr, NFS_sattr_sz << 2);
  
  	if (attr->ia_valid & ATTR_MODE)
  		*p++ = cpu_to_be32(attr->ia_mode);
  	else
  		*p++ = cpu_to_be32(NFS2_SATTR_NOT_SET);
  	if (attr->ia_valid & ATTR_UID)

  		*p++ = cpu_to_be32(from_kuid(&init_user_ns, attr->ia_uid));

  	else
  		*p++ = cpu_to_be32(NFS2_SATTR_NOT_SET);
  	if (attr->ia_valid & ATTR_GID)

  		*p++ = cpu_to_be32(from_kgid(&init_user_ns, attr->ia_gid));

  	else
  		*p++ = cpu_to_be32(NFS2_SATTR_NOT_SET);
  	if (attr->ia_valid & ATTR_SIZE)
  		*p++ = cpu_to_be32((u32)attr->ia_size);
  	else
  		*p++ = cpu_to_be32(NFS2_SATTR_NOT_SET);
  
  	if (attr->ia_valid & ATTR_ATIME_SET)
  		p = xdr_encode_time(p, &attr->ia_atime);
  	else if (attr->ia_valid & ATTR_ATIME)
  		p = xdr_encode_current_server_time(p, &attr->ia_atime);
  	else
  		p = xdr_time_not_set(p);
  	if (attr->ia_valid & ATTR_MTIME_SET)
  		xdr_encode_time(p, &attr->ia_mtime);
  	else if (attr->ia_valid & ATTR_MTIME)
  		xdr_encode_current_server_time(p, &attr->ia_mtime);
  	else
  		xdr_time_not_set(p);
  }
  
  /*
   * 2.3.7.  filename
   *
   *	typedef string filename<MAXNAMLEN>;
   */
  static void encode_filename(struct xdr_stream *xdr,
  			    const char *name, u32 length)
  {
  	__be32 *p;

  	WARN_ON_ONCE(length > NFS2_MAXNAMLEN);

  	p = xdr_reserve_space(xdr, 4 + length);
  	xdr_encode_opaque(p, name, length);
  }

  static int decode_filename_inline(struct xdr_stream *xdr,
  				  const char **name, u32 *length)
  {
  	__be32 *p;
  	u32 count;
  
  	p = xdr_inline_decode(xdr, 4);
  	if (unlikely(p == NULL))
  		goto out_overflow;
  	count = be32_to_cpup(p);
  	if (count > NFS3_MAXNAMLEN)
  		goto out_nametoolong;
  	p = xdr_inline_decode(xdr, count);
  	if (unlikely(p == NULL))
  		goto out_overflow;
  	*name = (const char *)p;
  	*length = count;
  	return 0;
  out_nametoolong:
  	dprintk("NFS: returned filename too long: %u
  ", count);
  	return -ENAMETOOLONG;
  out_overflow:
  	print_overflow_msg(__func__, xdr);
  	return -EIO;
  }

  /*
   * 2.3.8.  path
   *
   *	typedef string path<MAXPATHLEN>;
   */
  static void encode_path(struct xdr_stream *xdr, struct page **pages, u32 length)
  {
  	__be32 *p;

  	p = xdr_reserve_space(xdr, 4);
  	*p = cpu_to_be32(length);
  	xdr_write_pages(xdr, pages, 0, length);
  }

  static int decode_path(struct xdr_stream *xdr)
  {
  	u32 length, recvd;

  	__be32 *p;
  
  	p = xdr_inline_decode(xdr, 4);
  	if (unlikely(p == NULL))
  		goto out_overflow;
  	length = be32_to_cpup(p);
  	if (unlikely(length >= xdr->buf->page_len || length > NFS_MAXPATHLEN))
  		goto out_size;

  	recvd = xdr_read_pages(xdr, length);

  	if (unlikely(length > recvd))
  		goto out_cheating;

  	xdr_terminate_string(xdr->buf, length);
  	return 0;
  out_size:
  	dprintk("NFS: returned pathname too long: %u
  ", length);
  	return -ENAMETOOLONG;
  out_cheating:
  	dprintk("NFS: server cheating in pathname result: "
  		"length %u > received %u
  ", length, recvd);
  	return -EIO;
  out_overflow:
  	print_overflow_msg(__func__, xdr);
  	return -EIO;
  }
  
  /*
   * 2.3.9.  attrstat
   *
   *	union attrstat switch (stat status) {
   *	case NFS_OK:
   *		fattr attributes;
   *	default:
   *		void;
   *	};
   */

  static int decode_attrstat(struct xdr_stream *xdr, struct nfs_fattr *result,
  			   __u32 *op_status)

  {
  	enum nfs_stat status;
  	int error;
  
  	error = decode_stat(xdr, &status);
  	if (unlikely(error))
  		goto out;

  	if (op_status)
  		*op_status = status;

  	if (status != NFS_OK)
  		goto out_default;
  	error = decode_fattr(xdr, result);
  out:
  	return error;
  out_default:
  	return nfs_stat_to_errno(status);
  }

  /*
   * 2.3.10.  diropargs
   *
   *	struct diropargs {
   *		fhandle  dir;
   *		filename name;
   *	};
   */
  static void encode_diropargs(struct xdr_stream *xdr, const struct nfs_fh *fh,
  			     const char *name, u32 length)
  {
  	encode_fhandle(xdr, fh);
  	encode_filename(xdr, name, length);
  }

  /*
   * 2.3.11.  diropres
   *
   *	union diropres switch (stat status) {
   *	case NFS_OK:
   *		struct {
   *			fhandle file;
   *			fattr   attributes;
   *		} diropok;
   *	default:
   *		void;
   *	};
   */
  static int decode_diropok(struct xdr_stream *xdr, struct nfs_diropok *result)
  {
  	int error;
  
  	error = decode_fhandle(xdr, result->fh);
  	if (unlikely(error))
  		goto out;
  	error = decode_fattr(xdr, result->fattr);
  out:
  	return error;
  }
  
  static int decode_diropres(struct xdr_stream *xdr, struct nfs_diropok *result)
  {
  	enum nfs_stat status;
  	int error;
  
  	error = decode_stat(xdr, &status);
  	if (unlikely(error))
  		goto out;
  	if (status != NFS_OK)
  		goto out_default;
  	error = decode_diropok(xdr, result);
  out:
  	return error;
  out_default:
  	return nfs_stat_to_errno(status);
  }

  
  /*

   * NFSv2 XDR encode functions
   *
   * NFSv2 argument types are defined in section 2.2 of RFC 1094:
   * "NFS: Network File System Protocol Specification".

   */

  static void nfs2_xdr_enc_fhandle(struct rpc_rqst *req,
  				 struct xdr_stream *xdr,

  				 const void *data)

  {

  	const struct nfs_fh *fh = data;

  	encode_fhandle(xdr, fh);

  }

  /*

   * 2.2.3.  sattrargs
   *
   *	struct sattrargs {
   *		fhandle file;
   *		sattr attributes;
   *	};
   */

  static void nfs2_xdr_enc_sattrargs(struct rpc_rqst *req,
  				   struct xdr_stream *xdr,

  				   const void *data)

  {

  	const struct nfs_sattrargs *args = data;

  	encode_fhandle(xdr, args->fh);
  	encode_sattr(xdr, args->sattr);

  }

  static void nfs2_xdr_enc_diropargs(struct rpc_rqst *req,
  				   struct xdr_stream *xdr,

  				   const void *data)

  {

  	const struct nfs_diropargs *args = data;

  	encode_diropargs(xdr, args->fh, args->name, args->len);

  }

  static void nfs2_xdr_enc_readlinkargs(struct rpc_rqst *req,
  				      struct xdr_stream *xdr,

  				      const void *data)

  {

  	const struct nfs_readlinkargs *args = data;

  	encode_fhandle(xdr, args->fh);

  	prepare_reply_buffer(req, args->pages, args->pgbase,
  					args->pglen, NFS_readlinkres_sz);

  }

  /*

   * 2.2.7.  readargs
   *
   *	struct readargs {
   *		fhandle file;
   *		unsigned offset;
   *		unsigned count;
   *		unsigned totalcount;
   *	};
   */
  static void encode_readargs(struct xdr_stream *xdr,

  			    const struct nfs_pgio_args *args)

  {
  	u32 offset = args->offset;
  	u32 count = args->count;
  	__be32 *p;
  
  	encode_fhandle(xdr, args->fh);
  
  	p = xdr_reserve_space(xdr, 4 + 4 + 4);
  	*p++ = cpu_to_be32(offset);
  	*p++ = cpu_to_be32(count);
  	*p = cpu_to_be32(count);
  }

  static void nfs2_xdr_enc_readargs(struct rpc_rqst *req,
  				  struct xdr_stream *xdr,

  				  const void *data)

  {

  	const struct nfs_pgio_args *args = data;

  	encode_readargs(xdr, args);

  	prepare_reply_buffer(req, args->pages, args->pgbase,
  					args->count, NFS_readres_sz);
  	req->rq_rcv_buf.flags |= XDRBUF_READ;

  }
  
  /*

   * 2.2.9.  writeargs
   *
   *	struct writeargs {
   *		fhandle file;
   *		unsigned beginoffset;
   *		unsigned offset;
   *		unsigned totalcount;
   *		nfsdata data;
   *	};
   */
  static void encode_writeargs(struct xdr_stream *xdr,

  			     const struct nfs_pgio_args *args)

  {
  	u32 offset = args->offset;
  	u32 count = args->count;
  	__be32 *p;
  
  	encode_fhandle(xdr, args->fh);
  
  	p = xdr_reserve_space(xdr, 4 + 4 + 4 + 4);
  	*p++ = cpu_to_be32(offset);
  	*p++ = cpu_to_be32(offset);
  	*p++ = cpu_to_be32(count);
  
  	/* nfsdata */
  	*p = cpu_to_be32(count);
  	xdr_write_pages(xdr, args->pages, args->pgbase, count);
  }

  static void nfs2_xdr_enc_writeargs(struct rpc_rqst *req,
  				   struct xdr_stream *xdr,

  				   const void *data)

  {

  	const struct nfs_pgio_args *args = data;

  	encode_writeargs(xdr, args);
  	xdr->buf->flags |= XDRBUF_WRITE;

  }
  
  /*

   * 2.2.10.  createargs
   *
   *	struct createargs {
   *		diropargs where;
   *		sattr attributes;
   *	};
   */

  static void nfs2_xdr_enc_createargs(struct rpc_rqst *req,
  				    struct xdr_stream *xdr,

  				    const void *data)

  {

  	const struct nfs_createargs *args = data;

  	encode_diropargs(xdr, args->fh, args->name, args->len);
  	encode_sattr(xdr, args->sattr);

  }

  static void nfs2_xdr_enc_removeargs(struct rpc_rqst *req,
  				    struct xdr_stream *xdr,

  				    const void *data)

  {

  	const struct nfs_removeargs *args = data;

  	encode_diropargs(xdr, args->fh, args->name.name, args->name.len);

  }
  
  /*

   * 2.2.12.  renameargs
   *
   *	struct renameargs {
   *		diropargs from;
   *		diropargs to;
   *	};
   */

  static void nfs2_xdr_enc_renameargs(struct rpc_rqst *req,
  				    struct xdr_stream *xdr,

  				    const void *data)

  {

  	const struct nfs_renameargs *args = data;

  	const struct qstr *old = args->old_name;
  	const struct qstr *new = args->new_name;

  	encode_diropargs(xdr, args->old_dir, old->name, old->len);
  	encode_diropargs(xdr, args->new_dir, new->name, new->len);

  }
  
  /*

   * 2.2.13.  linkargs
   *
   *	struct linkargs {
   *		fhandle from;
   *		diropargs to;
   *	};
   */

  static void nfs2_xdr_enc_linkargs(struct rpc_rqst *req,
  				  struct xdr_stream *xdr,

  				  const void *data)

  {

  	const struct nfs_linkargs *args = data;

  	encode_fhandle(xdr, args->fromfh);
  	encode_diropargs(xdr, args->tofh, args->toname, args->tolen);

  }
  
  /*

   * 2.2.14.  symlinkargs
   *
   *	struct symlinkargs {
   *		diropargs from;
   *		path to;
   *		sattr attributes;
   *	};
   */

  static void nfs2_xdr_enc_symlinkargs(struct rpc_rqst *req,
  				     struct xdr_stream *xdr,

  				     const void *data)

  {

  	const struct nfs_symlinkargs *args = data;

  	encode_diropargs(xdr, args->fromfh, args->fromname, args->fromlen);
  	encode_path(xdr, args->pages, args->pathlen);
  	encode_sattr(xdr, args->sattr);

  }
  
  /*

   * 2.2.17.  readdirargs
   *
   *	struct readdirargs {
   *		fhandle dir;
   *		nfscookie cookie;
   *		unsigned count;
   *	};
   */
  static void encode_readdirargs(struct xdr_stream *xdr,
  			       const struct nfs_readdirargs *args)
  {
  	__be32 *p;
  
  	encode_fhandle(xdr, args->fh);
  
  	p = xdr_reserve_space(xdr, 4 + 4);
  	*p++ = cpu_to_be32(args->cookie);
  	*p = cpu_to_be32(args->count);
  }

  static void nfs2_xdr_enc_readdirargs(struct rpc_rqst *req,
  				     struct xdr_stream *xdr,

  				     const void *data)

  {

  	const struct nfs_readdirargs *args = data;

  	encode_readdirargs(xdr, args);

  	prepare_reply_buffer(req, args->pages, 0,
  					args->count, NFS_readdirres_sz);

  }
  
  /*

   * NFSv2 XDR decode functions
   *
   * NFSv2 result types are defined in section 2.2 of RFC 1094:
   * "NFS: Network File System Protocol Specification".

   */

  static int nfs2_xdr_dec_stat(struct rpc_rqst *req, struct xdr_stream *xdr,

  			     void *__unused)
  {

  	enum nfs_stat status;
  	int error;

  	error = decode_stat(xdr, &status);

  	if (unlikely(error))
  		goto out;
  	if (status != NFS_OK)
  		goto out_default;
  out:
  	return error;
  out_default:
  	return nfs_stat_to_errno(status);
  }

  static int nfs2_xdr_dec_attrstat(struct rpc_rqst *req, struct xdr_stream *xdr,

  				 void *result)

  {

  	return decode_attrstat(xdr, result, NULL);

  }

  static int nfs2_xdr_dec_diropres(struct rpc_rqst *req, struct xdr_stream *xdr,

  				 void *result)

  {

  	return decode_diropres(xdr, result);

  }

  /*

   * 2.2.6.  readlinkres
   *
   *	union readlinkres switch (stat status) {
   *	case NFS_OK:
   *		path data;
   *	default:
   *		void;
   *	};
   */

  static int nfs2_xdr_dec_readlinkres(struct rpc_rqst *req,
  				    struct xdr_stream *xdr, void *__unused)

  {

  	enum nfs_stat status;
  	int error;

  	error = decode_stat(xdr, &status);

  	if (unlikely(error))
  		goto out;
  	if (status != NFS_OK)
  		goto out_default;

  	error = decode_path(xdr);

  out:
  	return error;
  out_default:
  	return nfs_stat_to_errno(status);
  }
  
  /*
   * 2.2.7.  readres
   *
   *	union readres switch (stat status) {
   *	case NFS_OK:
   *		fattr attributes;
   *		nfsdata data;
   *	default:
   *		void;
   *	};
   */

  static int nfs2_xdr_dec_readres(struct rpc_rqst *req, struct xdr_stream *xdr,

  				void *data)

  {

  	struct nfs_pgio_res *result = data;

  	enum nfs_stat status;
  	int error;

  	error = decode_stat(xdr, &status);

  	if (unlikely(error))
  		goto out;

  	result->op_status = status;

  	if (status != NFS_OK)
  		goto out_default;

  	error = decode_fattr(xdr, result->fattr);

  	if (unlikely(error))
  		goto out;

  	error = decode_nfsdata(xdr, result);

  out:
  	return error;
  out_default:
  	return nfs_stat_to_errno(status);
  }

  static int nfs2_xdr_dec_writeres(struct rpc_rqst *req, struct xdr_stream *xdr,

  				 void *data)

  {

  	struct nfs_pgio_res *result = data;

  	/* All NFSv2 writes are "file sync" writes */
  	result->verf->committed = NFS_FILE_SYNC;

  	return decode_attrstat(xdr, result->fattr, &result->op_status);

  }
  
  /**
   * nfs2_decode_dirent - Decode a single NFSv2 directory entry stored in
   *                      the local page cache.
   * @xdr: XDR stream where entry resides
   * @entry: buffer to fill in with entry data

   * @plus: boolean indicating whether this should be a readdirplus entry
   *

   * Returns zero if successful, otherwise a negative errno value is
   * returned.

   *
   * This function is not invoked during READDIR reply decoding, but
   * rather whenever an application invokes the getdents(2) system call
   * on a directory already in our cache.
   *
   * 2.2.17.  entry
   *
   *	struct entry {
   *		unsigned	fileid;
   *		filename	name;
   *		nfscookie	cookie;
   *		entry		*nextentry;
   *	};
   */

  int nfs2_decode_dirent(struct xdr_stream *xdr, struct nfs_entry *entry,

  		       bool plus)

  {
  	__be32 *p;
  	int error;
  
  	p = xdr_inline_decode(xdr, 4);
  	if (unlikely(p == NULL))
  		goto out_overflow;
  	if (*p++ == xdr_zero) {
  		p = xdr_inline_decode(xdr, 4);
  		if (unlikely(p == NULL))
  			goto out_overflow;
  		if (*p++ == xdr_zero)

  			return -EAGAIN;

  		entry->eof = 1;

  		return -EBADCOOKIE;

  	}
  
  	p = xdr_inline_decode(xdr, 4);
  	if (unlikely(p == NULL))
  		goto out_overflow;
  	entry->ino = be32_to_cpup(p);
  
  	error = decode_filename_inline(xdr, &entry->name, &entry->len);
  	if (unlikely(error))

  		return error;

  
  	/*
  	 * The type (size and byte order) of nfscookie isn't defined in
  	 * RFC 1094.  This implementation assumes that it's an XDR uint32.
  	 */
  	entry->prev_cookie = entry->cookie;
  	p = xdr_inline_decode(xdr, 4);
  	if (unlikely(p == NULL))
  		goto out_overflow;
  	entry->cookie = be32_to_cpup(p);
  
  	entry->d_type = DT_UNKNOWN;

  	return 0;

  
  out_overflow:
  	print_overflow_msg(__func__, xdr);

  	return -EAGAIN;

  }
  
  /*
   * 2.2.17.  readdirres
   *
   *	union readdirres switch (stat status) {
   *	case NFS_OK:
   *		struct {
   *			entry *entries;
   *			bool eof;
   *		} readdirok;
   *	default:
   *		void;
   *	};
   *
   * Read the directory contents into the page cache, but don't
   * touch them.  The actual decoding is done by nfs2_decode_dirent()
   * during subsequent nfs_readdir() calls.
   */
  static int decode_readdirok(struct xdr_stream *xdr)
  {

  	return xdr_read_pages(xdr, xdr->buf->page_len);

  }

  static int nfs2_xdr_dec_readdirres(struct rpc_rqst *req,
  				   struct xdr_stream *xdr, void *__unused)

  {

  	enum nfs_stat status;
  	int error;

  	error = decode_stat(xdr, &status);

  	if (unlikely(error))
  		goto out;
  	if (status != NFS_OK)
  		goto out_default;

  	error = decode_readdirok(xdr);

  out:
  	return error;
  out_default:
  	return nfs_stat_to_errno(status);
  }

  /*

   * 2.2.18.  statfsres
   *
   *	union statfsres (stat status) {
   *	case NFS_OK:
   *		struct {
   *			unsigned tsize;
   *			unsigned bsize;
   *			unsigned blocks;
   *			unsigned bfree;
   *			unsigned bavail;
   *		} info;
   *	default:
   *		void;
   *	};
   */
  static int decode_info(struct xdr_stream *xdr, struct nfs2_fsstat *result)
  {
  	__be32 *p;
  
  	p = xdr_inline_decode(xdr, NFS_info_sz << 2);
  	if (unlikely(p == NULL))
  		goto out_overflow;
  	result->tsize  = be32_to_cpup(p++);
  	result->bsize  = be32_to_cpup(p++);
  	result->blocks = be32_to_cpup(p++);
  	result->bfree  = be32_to_cpup(p++);
  	result->bavail = be32_to_cpup(p);
  	return 0;
  out_overflow:
  	print_overflow_msg(__func__, xdr);
  	return -EIO;
  }

  static int nfs2_xdr_dec_statfsres(struct rpc_rqst *req, struct xdr_stream *xdr,

  				  void *result)

  {

  	enum nfs_stat status;
  	int error;

  	error = decode_stat(xdr, &status);

  	if (unlikely(error))
  		goto out;
  	if (status != NFS_OK)
  		goto out_default;

  	error = decode_info(xdr, result);

  out:
  	return error;
  out_default:
  	return nfs_stat_to_errno(status);
  }
  
  
  /*

   * We need to translate between nfs status return values and
   * the local errno values which may not be the same.
   */

  static const struct {

  	int stat;
  	int errno;
  } nfs_errtbl[] = {
  	{ NFS_OK,		0		},

  	{ NFSERR_PERM,		-EPERM		},
  	{ NFSERR_NOENT,		-ENOENT		},
  	{ NFSERR_IO,		-errno_NFSERR_IO},
  	{ NFSERR_NXIO,		-ENXIO		},
  /*	{ NFSERR_EAGAIN,	-EAGAIN		}, */
  	{ NFSERR_ACCES,		-EACCES		},
  	{ NFSERR_EXIST,		-EEXIST		},
  	{ NFSERR_XDEV,		-EXDEV		},
  	{ NFSERR_NODEV,		-ENODEV		},
  	{ NFSERR_NOTDIR,	-ENOTDIR	},
  	{ NFSERR_ISDIR,		-EISDIR		},
  	{ NFSERR_INVAL,		-EINVAL		},
  	{ NFSERR_FBIG,		-EFBIG		},
  	{ NFSERR_NOSPC,		-ENOSPC		},
  	{ NFSERR_ROFS,		-EROFS		},
  	{ NFSERR_MLINK,		-EMLINK		},
  	{ NFSERR_NAMETOOLONG,	-ENAMETOOLONG	},
  	{ NFSERR_NOTEMPTY,	-ENOTEMPTY	},
  	{ NFSERR_DQUOT,		-EDQUOT		},
  	{ NFSERR_STALE,		-ESTALE		},
  	{ NFSERR_REMOTE,	-EREMOTE	},

  #ifdef EWFLUSH

  	{ NFSERR_WFLUSH,	-EWFLUSH	},

  #endif

  	{ NFSERR_BADHANDLE,	-EBADHANDLE	},
  	{ NFSERR_NOT_SYNC,	-ENOTSYNC	},
  	{ NFSERR_BAD_COOKIE,	-EBADCOOKIE	},
  	{ NFSERR_NOTSUPP,	-ENOTSUPP	},
  	{ NFSERR_TOOSMALL,	-ETOOSMALL	},

  	{ NFSERR_SERVERFAULT,	-EREMOTEIO	},

  	{ NFSERR_BADTYPE,	-EBADTYPE	},
  	{ NFSERR_JUKEBOX,	-EJUKEBOX	},
  	{ -1,			-EIO		}

  };

  /**
   * nfs_stat_to_errno - convert an NFS status code to a local errno
   * @status: NFS status code to convert
   *
   * Returns a local errno value, or -EIO if the NFS status code is
   * not recognized.  This function is used jointly by NFSv2 and NFSv3.

   */

  static int nfs_stat_to_errno(enum nfs_stat status)

  {
  	int i;
  
  	for (i = 0; nfs_errtbl[i].stat != -1; i++) {

  		if (nfs_errtbl[i].stat == (int)status)

  			return nfs_errtbl[i].errno;
  	}

  	dprintk("NFS: Unrecognized nfs status value: %u
  ", status);

  	return nfs_errtbl[i].errno;
  }

  #define PROC(proc, argtype, restype, timer)				\
  [NFSPROC_##proc] = {							\
  	.p_proc	    =  NFSPROC_##proc,					\

  	.p_encode   =  nfs2_xdr_enc_##argtype,				\

  	.p_decode   =  nfs2_xdr_dec_##restype,				\

  	.p_arglen   =  NFS_##argtype##_sz,				\
  	.p_replen   =  NFS_##restype##_sz,				\

  	.p_timer    =  timer,						\
  	.p_statidx  =  NFSPROC_##proc,					\
  	.p_name     =  #proc,						\

  	}

  const struct rpc_procinfo nfs_procedures[] = {

  	PROC(GETATTR,	fhandle,	attrstat,	1),
  	PROC(SETATTR,	sattrargs,	attrstat,	0),
  	PROC(LOOKUP,	diropargs,	diropres,	2),
  	PROC(READLINK,	readlinkargs,	readlinkres,	3),
  	PROC(READ,	readargs,	readres,	3),
  	PROC(WRITE,	writeargs,	writeres,	4),
  	PROC(CREATE,	createargs,	diropres,	0),
  	PROC(REMOVE,	removeargs,	stat,		0),
  	PROC(RENAME,	renameargs,	stat,		0),
  	PROC(LINK,	linkargs,	stat,		0),
  	PROC(SYMLINK,	symlinkargs,	stat,		0),
  	PROC(MKDIR,	createargs,	diropres,	0),
  	PROC(RMDIR,	diropargs,	stat,		0),
  	PROC(READDIR,	readdirargs,	readdirres,	3),
  	PROC(STATFS,	fhandle,	statfsres,	0),

  };

  static unsigned int nfs_version2_counts[ARRAY_SIZE(nfs_procedures)];

  const struct rpc_version nfs_version2 = {

  	.number			= 2,

  	.nrprocs		= ARRAY_SIZE(nfs_procedures),

  	.procs			= nfs_procedures,
  	.counts			= nfs_version2_counts,

  };