linux/fs/xfs/xfs_export.c
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   1/*
   2 * Copyright (c) 2004-2005 Silicon Graphics, Inc.
   3 * All Rights Reserved.
   4 *
   5 * This program is free software; you can redistribute it and/or
   6 * modify it under the terms of the GNU General Public License as
   7 * published by the Free Software Foundation.
   8 *
   9 * This program is distributed in the hope that it would be useful,
  10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 * GNU General Public License for more details.
  13 *
  14 * You should have received a copy of the GNU General Public License
  15 * along with this program; if not, write the Free Software Foundation,
  16 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17 */
  18#include "xfs.h"
  19#include "xfs_types.h"
  20#include "xfs_log.h"
  21#include "xfs_trans.h"
  22#include "xfs_sb.h"
  23#include "xfs_ag.h"
  24#include "xfs_dir2.h"
  25#include "xfs_mount.h"
  26#include "xfs_export.h"
  27#include "xfs_vnodeops.h"
  28#include "xfs_bmap_btree.h"
  29#include "xfs_inode.h"
  30#include "xfs_inode_item.h"
  31#include "xfs_trace.h"
  32#include "xfs_icache.h"
  33
  34/*
  35 * Note that we only accept fileids which are long enough rather than allow
  36 * the parent generation number to default to zero.  XFS considers zero a
  37 * valid generation number not an invalid/wildcard value.
  38 */
  39static int xfs_fileid_length(int fileid_type)
  40{
  41        switch (fileid_type) {
  42        case FILEID_INO32_GEN:
  43                return 2;
  44        case FILEID_INO32_GEN_PARENT:
  45                return 4;
  46        case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
  47                return 3;
  48        case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
  49                return 6;
  50        }
  51        return FILEID_INVALID;
  52}
  53
  54STATIC int
  55xfs_fs_encode_fh(
  56        struct inode    *inode,
  57        __u32           *fh,
  58        int             *max_len,
  59        struct inode    *parent)
  60{
  61        struct fid              *fid = (struct fid *)fh;
  62        struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fh;
  63        int                     fileid_type;
  64        int                     len;
  65
  66        /* Directories don't need their parent encoded, they have ".." */
  67        if (!parent)
  68                fileid_type = FILEID_INO32_GEN;
  69        else
  70                fileid_type = FILEID_INO32_GEN_PARENT;
  71
  72        /*
  73         * If the the filesystem may contain 64bit inode numbers, we need
  74         * to use larger file handles that can represent them.
  75         *
  76         * While we only allocate inodes that do not fit into 32 bits any
  77         * large enough filesystem may contain them, thus the slightly
  78         * confusing looking conditional below.
  79         */
  80        if (!(XFS_M(inode->i_sb)->m_flags & XFS_MOUNT_SMALL_INUMS) ||
  81            (XFS_M(inode->i_sb)->m_flags & XFS_MOUNT_32BITINODES))
  82                fileid_type |= XFS_FILEID_TYPE_64FLAG;
  83
  84        /*
  85         * Only encode if there is enough space given.  In practice
  86         * this means we can't export a filesystem with 64bit inodes
  87         * over NFSv2 with the subtree_check export option; the other
  88         * seven combinations work.  The real answer is "don't use v2".
  89         */
  90        len = xfs_fileid_length(fileid_type);
  91        if (*max_len < len) {
  92                *max_len = len;
  93                return FILEID_INVALID;
  94        }
  95        *max_len = len;
  96
  97        switch (fileid_type) {
  98        case FILEID_INO32_GEN_PARENT:
  99                fid->i32.parent_ino = XFS_I(parent)->i_ino;
 100                fid->i32.parent_gen = parent->i_generation;
 101                /*FALLTHRU*/
 102        case FILEID_INO32_GEN:
 103                fid->i32.ino = XFS_I(inode)->i_ino;
 104                fid->i32.gen = inode->i_generation;
 105                break;
 106        case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 107                fid64->parent_ino = XFS_I(parent)->i_ino;
 108                fid64->parent_gen = parent->i_generation;
 109                /*FALLTHRU*/
 110        case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
 111                fid64->ino = XFS_I(inode)->i_ino;
 112                fid64->gen = inode->i_generation;
 113                break;
 114        }
 115
 116        return fileid_type;
 117}
 118
 119STATIC struct inode *
 120xfs_nfs_get_inode(
 121        struct super_block      *sb,
 122        u64                     ino,
 123        u32                     generation)
 124 {
 125        xfs_mount_t             *mp = XFS_M(sb);
 126        xfs_inode_t             *ip;
 127        int                     error;
 128
 129        /*
 130         * NFS can sometimes send requests for ino 0.  Fail them gracefully.
 131         */
 132        if (ino == 0)
 133                return ERR_PTR(-ESTALE);
 134
 135        /*
 136         * The XFS_IGET_UNTRUSTED means that an invalid inode number is just
 137         * fine and not an indication of a corrupted filesystem as clients can
 138         * send invalid file handles and we have to handle it gracefully..
 139         */
 140        error = xfs_iget(mp, NULL, ino, XFS_IGET_UNTRUSTED, 0, &ip);
 141        if (error) {
 142                /*
 143                 * EINVAL means the inode cluster doesn't exist anymore.
 144                 * This implies the filehandle is stale, so we should
 145                 * translate it here.
 146                 * We don't use ESTALE directly down the chain to not
 147                 * confuse applications using bulkstat that expect EINVAL.
 148                 */
 149                if (error == EINVAL || error == ENOENT)
 150                        error = ESTALE;
 151                return ERR_PTR(-error);
 152        }
 153
 154        if (ip->i_d.di_gen != generation) {
 155                IRELE(ip);
 156                return ERR_PTR(-ESTALE);
 157        }
 158
 159        return VFS_I(ip);
 160}
 161
 162STATIC struct dentry *
 163xfs_fs_fh_to_dentry(struct super_block *sb, struct fid *fid,
 164                 int fh_len, int fileid_type)
 165{
 166        struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
 167        struct inode            *inode = NULL;
 168
 169        if (fh_len < xfs_fileid_length(fileid_type))
 170                return NULL;
 171
 172        switch (fileid_type) {
 173        case FILEID_INO32_GEN_PARENT:
 174        case FILEID_INO32_GEN:
 175                inode = xfs_nfs_get_inode(sb, fid->i32.ino, fid->i32.gen);
 176                break;
 177        case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 178        case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
 179                inode = xfs_nfs_get_inode(sb, fid64->ino, fid64->gen);
 180                break;
 181        }
 182
 183        return d_obtain_alias(inode);
 184}
 185
 186STATIC struct dentry *
 187xfs_fs_fh_to_parent(struct super_block *sb, struct fid *fid,
 188                 int fh_len, int fileid_type)
 189{
 190        struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
 191        struct inode            *inode = NULL;
 192
 193        if (fh_len < xfs_fileid_length(fileid_type))
 194                return NULL;
 195
 196        switch (fileid_type) {
 197        case FILEID_INO32_GEN_PARENT:
 198                inode = xfs_nfs_get_inode(sb, fid->i32.parent_ino,
 199                                              fid->i32.parent_gen);
 200                break;
 201        case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 202                inode = xfs_nfs_get_inode(sb, fid64->parent_ino,
 203                                              fid64->parent_gen);
 204                break;
 205        }
 206
 207        return d_obtain_alias(inode);
 208}
 209
 210STATIC struct dentry *
 211xfs_fs_get_parent(
 212        struct dentry           *child)
 213{
 214        int                     error;
 215        struct xfs_inode        *cip;
 216
 217        error = xfs_lookup(XFS_I(child->d_inode), &xfs_name_dotdot, &cip, NULL);
 218        if (unlikely(error))
 219                return ERR_PTR(-error);
 220
 221        return d_obtain_alias(VFS_I(cip));
 222}
 223
 224STATIC int
 225xfs_fs_nfs_commit_metadata(
 226        struct inode            *inode)
 227{
 228        struct xfs_inode        *ip = XFS_I(inode);
 229        struct xfs_mount        *mp = ip->i_mount;
 230        xfs_lsn_t               lsn = 0;
 231
 232        xfs_ilock(ip, XFS_ILOCK_SHARED);
 233        if (xfs_ipincount(ip))
 234                lsn = ip->i_itemp->ili_last_lsn;
 235        xfs_iunlock(ip, XFS_ILOCK_SHARED);
 236
 237        if (!lsn)
 238                return 0;
 239        return _xfs_log_force_lsn(mp, lsn, XFS_LOG_SYNC, NULL);
 240}
 241
 242const struct export_operations xfs_export_operations = {
 243        .encode_fh              = xfs_fs_encode_fh,
 244        .fh_to_dentry           = xfs_fs_fh_to_dentry,
 245        .fh_to_parent           = xfs_fs_fh_to_parent,
 246        .get_parent             = xfs_fs_get_parent,
 247        .commit_metadata        = xfs_fs_nfs_commit_metadata,
 248};
 249
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