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Make XFS provide encoding and decoding callbacks from knfsd which encode
the fileid portion of the NFS filehandle differently than the default
functions.  The new fileid formats allow filesystems mounted with "inode64"
to be exported over NFSv3 (and NFSv2 if you also use the "no_subtree_check"
export option).  For filesystems without "inode64", the file handles are
binary compatible with the old ones, so it should be possible to upgrade a
server without unmounting clients.
Merge of xfs-linux-melb:xfs-kern:21686a by kenmcd.

  Fix interaction between XFS with 64 bit inodes enabled and NFS.

/*
 * Copyright (c) 2005 Silicon Graphics, Inc.  All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *
 * Further, this software is distributed without any warranty that it is
 * free of the rightful claim of any third person regarding infringement
 * or the like.  Any license provided herein, whether implied or
 * otherwise, applies only to this software file.  Patent licenses, if
 * any, provided herein do not apply to combinations of this program with
 * other software, or any other product whatsoever.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write the Free Software Foundation, Inc., 59
 * Temple Place - Suite 330, Boston MA 02111-1307, USA.
 *
 * Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
 * Mountain View, CA  94043, or:
 *
 * http://www.sgi.com
 *
 * For further information regarding this notice, see:
 *
 * http://oss.sgi.com/projects/GenInfo/SGIGPLNoticeExplan/
 */
#ifndef __XFS_EXPORT_H__
#define __XFS_EXPORT_H__

/*
 * Common defines for code related to exporting XFS filesystems over NFS.
 *
 * The NFS fileid goes out on the wire as an array of
 * 32bit unsigned ints in host order.  There are 5 possible
 * formats.
 *
 * (1)	fileid_type=0x00
 *	(no fileid data; handled by the generic code)
 *
 * (2)	fileid_type=0x01
 *	inode-num
 *	generation
 *
 * (3)	fileid_type=0x02
 *	inode-num
 *	generation
 *	parent-inode-num
 *	parent-generation
 *
 * (4)	fileid_type=0x81
 *	inode-num-lo32
 *	inode-num-hi32
 *	generation
 *
 * (5)	fileid_type=0x82
 *	inode-num-lo32
 *	inode-num-hi32
 *	generation
 *	parent-inode-num-lo32
 *	parent-inode-num-hi32
 *	parent-generation
 *
 * Note, the NFS filehandle also includes an fsid portion which
 * may have an inode number in it.  That number is hardcoded to
 * 32bits and there is no way for XFS to intercept it.  In
 * practice this means when exporting an XFS filesytem with 64bit
 * inodes you should either export the mountpoint (rather than
 * a subdirectory) or use the "fsid" export option.
 */

/* This flag goes on the wire.  Don't play with it. */
#define XFS_FILEID_TYPE_64FLAG	0x80	/* NFS fileid has 64bit inodes */

/* Calculate the length in u32 units of the fileid data */
static inline int
xfs_fileid_length(int hasparent, int is64)
{
	return hasparent ? (is64 ? 6 : 4) : (is64 ? 3 : 2);
}

/*
 * Decode encoded inode information (either for the inode itself
 * or the parent) into an xfs_fid2_t structure.  Advances and
 * returns the new data pointer
 */
static inline __u32 *
xfs_fileid_decode_fid2(__u32 *p, xfs_fid2_t *fid, int is64)
{
	fid->fid_len = sizeof(xfs_fid2_t) - sizeof(fid->fid_len);
	fid->fid_pad = 0;
	fid->fid_ino = *p++;
#if XFS_BIG_INUMS
	if (is64)
		fid->fid_ino |= (((__u64)(*p++)) << 32);
#endif
	fid->fid_gen = *p++;
	return p;
}

/*
 * Encode inode information (either for the inode itself or the
 * parent) into a fileid buffer.  Advances and returns the new
 * data pointer.
 */
static inline __u32 *
xfs_fileid_encode_inode(__u32 *p, struct inode *inode, int is64)
{
	*p++ = (__u32)inode->i_ino;
#if XFS_BIG_INUMS
	if (is64)
		*p++ = (__u32)(inode->i_ino >> 32);
#endif
	*p++ = inode->i_generation;
	return p;
}

#endif	/* __XFS_EXPORT_H__ */