/*
 * 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, };

/*
 * 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.
 */
static int xfs_fileid_length(int fileid_type)
{
        switch (fileid_type) {
        case FILEID_INO32_GEN:
                return 2;
        case FILEID_INO32_GEN_PARENT:
                return 4;
        case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
                return 3;
        case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
                return 6;
        }
        return 255; /* invalid */
}

STATIC int
xfs_fs_encode_fh(
        struct dentry           *dentry,
        __u32                   *fh,
        int                     *max_len,
        int                     connectable)
{
        struct fid              *fid = (struct fid *)fh;
        struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fh;
        struct inode            *inode = dentry->d_inode;
        int                     fileid_type;
        int                     len;

        /* Directories don't need their parent encoded, they have ".." */
        if (S_ISDIR(inode->i_mode))
                fileid_type = FILEID_INO32_GEN;
        else
                fileid_type = FILEID_INO32_GEN_PARENT;

        /* filesystem may contain 64bit inode numbers */
        if (!(XFS_M(inode->i_sb)->m_flags & XFS_MOUNT_SMALL_INUMS))
                fileid_type |= XFS_FILEID_TYPE_64FLAG;

        /*
         * 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(fileid_type);
        if (*max_len < len)
                return 255;
        *max_len = len;

        switch (fileid_type) {
        case FILEID_INO32_GEN_PARENT:
                spin_lock(&dentry->d_lock);
                fid->i32.parent_ino = dentry->d_parent->d_inode->i_ino;
                fid->i32.parent_gen = dentry->d_parent->d_inode->i_generation;
                spin_unlock(&dentry->d_lock);
                /*FALLTHRU*/
        case FILEID_INO32_GEN:
                fid->i32.ino = inode->i_ino;
                fid->i32.gen = inode->i_generation;
                break;
        case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
                spin_lock(&dentry->d_lock);
                fid64->parent_ino = dentry->d_parent->d_inode->i_ino;
                fid64->parent_gen = dentry->d_parent->d_inode->i_generation;
                spin_unlock(&dentry->d_lock);
                /*FALLTHRU*/
        case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
                fid64->ino = inode->i_ino;
                fid64->gen = inode->i_generation;
                break;
        }

        return fileid_type;
}

STATIC struct inode *
xfs_nfs_get_inode(
        struct super_block      *sb,
        u64                     ino,
        u32                     generation)
 {
        xfs_fid_t               xfid;
        bhv_vnode_t             *vp;
        int                     error;

        xfid.fid_len = sizeof(xfs_fid_t) - sizeof(xfid.fid_len);
        xfid.fid_pad = 0;
        xfid.fid_ino = ino;
        xfid.fid_gen = generation;

        error = xfs_vget(XFS_M(sb), &vp, &xfid);
        if (error)
                return ERR_PTR(-error);

        return vp ? vn_to_inode(vp) : NULL;
}

STATIC struct dentry *
xfs_fs_fh_to_dentry(struct super_block *sb, struct fid *fid,
                 int fh_len, int fileid_type)
{
        struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
        struct inode            *inode = NULL;
        struct dentry           *result;

        if (fh_len < xfs_fileid_length(fileid_type))
                return NULL;

        switch (fileid_type) {
        case FILEID_INO32_GEN_PARENT:
        case FILEID_INO32_GEN:
                inode = xfs_nfs_get_inode(sb, fid->i32.ino, fid->i32.gen);
                break;
        case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
        case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
                inode = xfs_nfs_get_inode(sb, fid64->ino, fid64->gen);
                break;
        }

        if (!inode)
                return NULL;
        if (IS_ERR(inode))
                return ERR_PTR(PTR_ERR(inode));
        result = d_alloc_anon(inode);
        if (!result) {
                iput(inode);
                return ERR_PTR(-ENOMEM);
        }
        return result;
}

STATIC struct dentry *
xfs_fs_fh_to_parent(struct super_block *sb, struct fid *fid,
                 int fh_len, int fileid_type)
{
        struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
        struct inode            *inode = NULL;
        struct dentry           *result;

        switch (fileid_type) {
        case FILEID_INO32_GEN_PARENT:
                inode = xfs_nfs_get_inode(sb, fid->i32.parent_ino,
                                              fid->i32.parent_gen);
                break;
        case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
                inode = xfs_nfs_get_inode(sb, fid64->parent_ino,
                                              fid64->parent_gen);
                break;
        }

        if (!inode)
                return NULL;
        if (IS_ERR(inode))
                return ERR_PTR(PTR_ERR(inode));
        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;
}

const struct export_operations xfs_export_operations = {
        .encode_fh              = xfs_fs_encode_fh,
        .fh_to_dentry           = xfs_fs_fh_to_dentry,
        .fh_to_parent           = xfs_fs_fh_to_parent,
        .get_parent             = xfs_fs_get_parent,
};