xfs_export.c

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/*
 * 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"

/*
 * 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 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 255;
    }
    *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,
};