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cleanup fid types mess

Currently XFs has three different fid types: struct fid, struct xfs_fid
and struct xfs_fid2 with hte latter two beeing identicaly and the first
one beeing the same size but an unstructured array with the same size.

This patch consolidates all this to alway uuse struct xfs_fid.

This patch is required for an upcoming patch series from me that revamps
the nfs exporting code and introduces a Linux-wide struct fid.


Note: the patch is ontop of Eric's inode/vnode tracing cleanup.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Merge of xfs-linux-melb:xfs-kern:29651a by kenmcd.

  cleanup fid types mess

/*
 * Copyright (c) 2004-2005 Silicon Graphics, Inc.
 * All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms 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.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#include "xfs.h"
#include "xfs_types.h"
#include "xfs_inum.h"
#include "xfs_log.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_dmapi.h"
#include "xfs_mount.h"
#include "xfs_export.h"
#include "xfs_vnodeops.h"
#include "xfs_bmap_btree.h"
#include "xfs_inode.h"
#include "xfs_vfsops.h"

static struct dentry dotdot = { .d_name.name = "..", .d_name.len = 2, };

/*
 * XFS encodes and decodes the fileid portion of NFS filehandles
 * itself instead of letting the generic NFS code do it.  This
 * allows filesystems with 64 bit inode numbers to be exported.
 *
 * Note that a side effect is that xfs_vget() won't be passed a
 * zero inode/generation pair under normal circumstances.  As
 * however a malicious client could send us such data, the check
 * remains in that code.
 */

STATIC struct dentry *
xfs_fs_decode_fh(
	struct super_block	*sb,
	__u32			*fh,
	int			fh_len,
	int			fileid_type,
	int (*acceptable)(
		void		*context,
		struct dentry	*de),
	void			*context)
{
	xfs_fid_t		ifid;
	xfs_fid_t		pfid;
	void			*parent = NULL;
	int			is64 = 0;
	__u32			*p = fh;

#if XFS_BIG_INUMS
	is64 = (fileid_type & XFS_FILEID_TYPE_64FLAG);
	fileid_type &= ~XFS_FILEID_TYPE_64FLAG;
#endif

	/*
	 * Note that we only accept fileids which are long enough
	 * rather than allow the parent generation number to default
	 * to zero.  XFS considers zero a valid generation number not
	 * an invalid/wildcard value.  There's little point printk'ing
	 * a warning here as we don't have the client information
	 * which would make such a warning useful.
	 */
	if (fileid_type > 2 ||
	    fh_len < xfs_fileid_length((fileid_type == 2), is64))
		return NULL;

	p = xfs_fileid_decode_fid2(p, &ifid, is64);

	if (fileid_type == 2) {
		p = xfs_fileid_decode_fid2(p, &pfid, is64);
		parent = &pfid;
	}

	fh = (__u32 *)&ifid;
	return sb->s_export_op->find_exported_dentry(sb, fh, parent, acceptable, context);
}


STATIC int
xfs_fs_encode_fh(
	struct dentry		*dentry,
	__u32			*fh,
	int			*max_len,
	int			connectable)
{
	struct inode		*inode = dentry->d_inode;
	int			type = 1;
	__u32			*p = fh;
	int			len;
	int			is64 = 0;
#if XFS_BIG_INUMS
	if (!(XFS_M(inode->i_sb)->m_flags & XFS_MOUNT_SMALL_INUMS)) {
		/* filesystem may contain 64bit inode numbers */
		is64 = XFS_FILEID_TYPE_64FLAG;
	}
#endif

	/* Directories don't need their parent encoded, they have ".." */
	if (S_ISDIR(inode->i_mode))
	    connectable = 0;

	/*
	 * Only encode if there is enough space given.  In practice
	 * this means we can't export a filesystem with 64bit inodes
	 * over NFSv2 with the subtree_check export option; the other
	 * seven combinations work.  The real answer is "don't use v2".
	 */
	len = xfs_fileid_length(connectable, is64);
	if (*max_len < len)
		return 255;
	*max_len = len;

	p = xfs_fileid_encode_inode(p, inode, is64);
	if (connectable) {
		spin_lock(&dentry->d_lock);
		p = xfs_fileid_encode_inode(p, dentry->d_parent->d_inode, is64);
		spin_unlock(&dentry->d_lock);
		type = 2;
	}
	BUG_ON((p - fh) != len);
	return type | is64;
}

STATIC struct dentry *
xfs_fs_get_dentry(
	struct super_block	*sb,
	void			*data)
{
	bhv_vnode_t		*vp;
	struct inode		*inode;
	struct dentry		*result;
	int			error;

	error = xfs_vget(XFS_M(sb), &vp, data);
	if (error || vp == NULL)
		return ERR_PTR(-ESTALE) ;

	inode = vn_to_inode(vp);
	result = d_alloc_anon(inode);
        if (!result) {
		iput(inode);
		return ERR_PTR(-ENOMEM);
	}
	return result;
}

STATIC struct dentry *
xfs_fs_get_parent(
	struct dentry		*child)
{
	int			error;
	bhv_vnode_t		*cvp;
	struct dentry		*parent;

	cvp = NULL;
	error = xfs_lookup(XFS_I(child->d_inode), &dotdot, &cvp);
	if (unlikely(error))
		return ERR_PTR(-error);

	parent = d_alloc_anon(vn_to_inode(cvp));
	if (unlikely(!parent)) {
		VN_RELE(cvp);
		return ERR_PTR(-ENOMEM);
	}
	return parent;
}

struct export_operations xfs_export_operations = {
	.decode_fh		= xfs_fs_decode_fh,
	.encode_fh		= xfs_fs_encode_fh,
	.get_parent		= xfs_fs_get_parent,
	.get_dentry		= xfs_fs_get_dentry,
};