/*
 * 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_log.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_dir2.h"
#include "xfs_mount.h"
#include "xfs_export.h"
#include "xfs_vnodeops.h"
#include "xfs_bmap_btree.h"
#include "xfs_inode.h"
#include "xfs_inode_item.h"
#include "xfs_trace.h"
#include "xfs_icache.h"

/*
 * 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 FILEID_INVALID;
}

STATIC int
xfs_fs_encode_fh(
        struct inode    *inode,
        __u32           *fh,
        int             *max_len,
        struct inode    *parent)
{
        struct fid              *fid = (struct fid *)fh;
        struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fh;
        int                     fileid_type;
        int                     len;

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

        /*
         * If the the filesystem may contain 64bit inode numbers, we need
         * to use larger file handles that can represent them.
         *
         * While we only allocate inodes that do not fit into 32 bits any
         * large enough filesystem may contain them, thus the slightly
         * confusing looking conditional below.
         */
        if (!(XFS_M(inode->i_sb)->m_flags & XFS_MOUNT_SMALL_INUMS) ||
            (XFS_M(inode->i_sb)->m_flags & XFS_MOUNT_32BITINODES))
                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) {
                *max_len = len;
                return FILEID_INVALID;
        }
        *max_len = len;

        switch (fileid_type) {
        case FILEID_INO32_GEN_PARENT:
                fid->i32.parent_ino = XFS_I(parent)->i_ino;
                fid->i32.parent_gen = parent->i_generation;
                /*FALLTHRU*/
        case FILEID_INO32_GEN:
                fid->i32.ino = XFS_I(inode)->i_ino;
                fid->i32.gen = inode->i_generation;
                break;
        case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
                fid64->parent_ino = XFS_I(parent)->i_ino;
                fid64->parent_gen = parent->i_generation;
                /*FALLTHRU*/
        case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
                fid64->ino = XFS_I(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_mount_t             *mp = XFS_M(sb);
        xfs_inode_t             *ip;
        int                     error;

        /*
         * NFS can sometimes send requests for ino 0.  Fail them gracefully.
         */
        if (ino == 0)
                return ERR_PTR(-ESTALE);

        /*
         * The XFS_IGET_UNTRUSTED means that an invalid inode number is just
         * fine and not an indication of a corrupted filesystem as clients can
         * send invalid file handles and we have to handle it gracefully..
         */
        error = xfs_iget(mp, NULL, ino, XFS_IGET_UNTRUSTED, 0, &ip);
        if (error) {
                /*
                 * EINVAL means the inode cluster doesn't exist anymore.
                 * This implies the filehandle is stale, so we should
                 * translate it here.
                 * We don't use ESTALE directly down the chain to not
                 * confuse applications using bulkstat that expect EINVAL.
                 */
                if (error == EINVAL || error == ENOENT)
                        error = ESTALE;
                return ERR_PTR(-error);
        }

        if (ip->i_d.di_gen != generation) {
                IRELE(ip);
                return ERR_PTR(-ESTALE);
        }

        return VFS_I(ip);
}

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;

        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;
        }

        return d_obtain_alias(inode);
}

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;

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

        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;
        }

        return d_obtain_alias(inode);
}

STATIC struct dentry *
xfs_fs_get_parent(
        struct dentry           *child)
{
        int                     error;
        struct xfs_inode        *cip;

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

        return d_obtain_alias(VFS_I(cip));
}

STATIC int
xfs_fs_nfs_commit_metadata(
        struct inode            *inode)
{
        struct xfs_inode        *ip = XFS_I(inode);
        struct xfs_mount        *mp = ip->i_mount;
        xfs_lsn_t               lsn = 0;

        xfs_ilock(ip, XFS_ILOCK_SHARED);
        if (xfs_ipincount(ip))
                lsn = ip->i_itemp->ili_last_lsn;
        xfs_iunlock(ip, XFS_ILOCK_SHARED);

        if (!lsn)
                return 0;
        return _xfs_log_force_lsn(mp, lsn, XFS_LOG_SYNC, NULL);
}

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,
        .commit_metadata        = xfs_fs_nfs_commit_metadata,
};