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
  33/*
  34 * Note that we only accept fileids which are long enough rather than allow
  35 * the parent generation number to default to zero.  XFS considers zero a
  36 * valid generation number not an invalid/wildcard value.
  37 */
  38static int xfs_fileid_length(int fileid_type)
  39{
  40        switch (fileid_type) {
  41        case FILEID_INO32_GEN:
  42                return 2;
  43        case FILEID_INO32_GEN_PARENT:
  44                return 4;
  45        case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
  46                return 3;
  47        case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
  48                return 6;
  49        }
  50        return 255; /* invalid */
  51}
  52
  53STATIC int
  54xfs_fs_encode_fh(
  55        struct inode    *inode,
  56        __u32           *fh,
  57        int             *max_len,
  58        struct inode    *parent)
  59{
  60        struct fid              *fid = (struct fid *)fh;
  61        struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fh;
  62        int                     fileid_type;
  63        int                     len;
  64
  65        /* Directories don't need their parent encoded, they have ".." */
  66        if (!parent)
  67                fileid_type = FILEID_INO32_GEN;
  68        else
  69                fileid_type = FILEID_INO32_GEN_PARENT;
  70
  71        /*
  72         * If the the filesystem may contain 64bit inode numbers, we need
  73         * to use larger file handles that can represent them.
  74         *
  75         * While we only allocate inodes that do not fit into 32 bits any
  76         * large enough filesystem may contain them, thus the slightly
  77         * confusing looking conditional below.
  78         */
  79        if (!(XFS_M(inode->i_sb)->m_flags & XFS_MOUNT_SMALL_INUMS) ||
  80            (XFS_M(inode->i_sb)->m_flags & XFS_MOUNT_32BITINODES))
  81                fileid_type |= XFS_FILEID_TYPE_64FLAG;
  82
  83        /*
  84         * Only encode if there is enough space given.  In practice
  85         * this means we can't export a filesystem with 64bit inodes
  86         * over NFSv2 with the subtree_check export option; the other
  87         * seven combinations work.  The real answer is "don't use v2".
  88         */
  89        len = xfs_fileid_length(fileid_type);
  90        if (*max_len < len) {
  91                *max_len = len;
  92                return 255;
  93        }
  94        *max_len = len;
  95
  96        switch (fileid_type) {
  97        case FILEID_INO32_GEN_PARENT:
  98                fid->i32.parent_ino = XFS_I(parent)->i_ino;
  99                fid->i32.parent_gen = parent->i_generation;
 100                /*FALLTHRU*/
 101        case FILEID_INO32_GEN:
 102                fid->i32.ino = XFS_I(inode)->i_ino;
 103                fid->i32.gen = inode->i_generation;
 104                break;
 105        case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 106                fid64->parent_ino = XFS_I(parent)->i_ino;
 107                fid64->parent_gen = parent->i_generation;
 108                /*FALLTHRU*/
 109        case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
 110                fid64->ino = XFS_I(inode)->i_ino;
 111                fid64->gen = inode->i_generation;
 112                break;
 113        }
 114
 115        return fileid_type;
 116}
 117
 118STATIC struct inode *
 119xfs_nfs_get_inode(
 120        struct super_block      *sb,
 121        u64                     ino,
 122        u32                     generation)
 123 {
 124        xfs_mount_t             *mp = XFS_M(sb);
 125        xfs_inode_t             *ip;
 126        int                     error;
 127
 128        /*
 129         * NFS can sometimes send requests for ino 0.  Fail them gracefully.
 130         */
 131        if (ino == 0)
 132                return ERR_PTR(-ESTALE);
 133
 134        /*
 135         * The XFS_IGET_UNTRUSTED means that an invalid inode number is just
 136         * fine and not an indication of a corrupted filesystem as clients can
 137         * send invalid file handles and we have to handle it gracefully..
 138         */
 139        error = xfs_iget(mp, NULL, ino, XFS_IGET_UNTRUSTED, 0, &ip);
 140        if (error) {
 141                /*
 142                 * EINVAL means the inode cluster doesn't exist anymore.
 143                 * This implies the filehandle is stale, so we should
 144                 * translate it here.
 145                 * We don't use ESTALE directly down the chain to not
 146                 * confuse applications using bulkstat that expect EINVAL.
 147                 */
 148                if (error == EINVAL || error == ENOENT)
 149                        error = ESTALE;
 150                return ERR_PTR(-error);
 151        }
 152
 153        if (ip->i_d.di_gen != generation) {
 154                IRELE(ip);
 155                return ERR_PTR(-ESTALE);
 156        }
 157
 158        return VFS_I(ip);
 159}
 160
 161STATIC struct dentry *
 162xfs_fs_fh_to_dentry(struct super_block *sb, struct fid *fid,
 163                 int fh_len, int fileid_type)
 164{
 165        struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
 166        struct inode            *inode = NULL;
 167
 168        if (fh_len < xfs_fileid_length(fileid_type))
 169                return NULL;
 170
 171        switch (fileid_type) {
 172        case FILEID_INO32_GEN_PARENT:
 173        case FILEID_INO32_GEN:
 174                inode = xfs_nfs_get_inode(sb, fid->i32.ino, fid->i32.gen);
 175                break;
 176        case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 177        case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
 178                inode = xfs_nfs_get_inode(sb, fid64->ino, fid64->gen);
 179                break;
 180        }
 181
 182        return d_obtain_alias(inode);
 183}
 184
 185STATIC struct dentry *
 186xfs_fs_fh_to_parent(struct super_block *sb, struct fid *fid,
 187                 int fh_len, int fileid_type)
 188{
 189        struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
 190        struct inode            *inode = NULL;
 191
 192        if (fh_len < xfs_fileid_length(fileid_type))
 193                return NULL;
 194
 195        switch (fileid_type) {
 196        case FILEID_INO32_GEN_PARENT:
 197                inode = xfs_nfs_get_inode(sb, fid->i32.parent_ino,
 198                                              fid->i32.parent_gen);
 199                break;
 200        case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 201                inode = xfs_nfs_get_inode(sb, fid64->parent_ino,
 202                                              fid64->parent_gen);
 203                break;
 204        }
 205
 206        return d_obtain_alias(inode);
 207}
 208
 209STATIC struct dentry *
 210xfs_fs_get_parent(
 211        struct dentry           *child)
 212{
 213        int                     error;
 214        struct xfs_inode        *cip;
 215
 216        error = xfs_lookup(XFS_I(child->d_inode), &xfs_name_dotdot, &cip, NULL);
 217        if (unlikely(error))
 218                return ERR_PTR(-error);
 219
 220        return d_obtain_alias(VFS_I(cip));
 221}
 222
 223STATIC int
 224xfs_fs_nfs_commit_metadata(
 225        struct inode            *inode)
 226{
 227        struct xfs_inode        *ip = XFS_I(inode);
 228        struct xfs_mount        *mp = ip->i_mount;
 229        xfs_lsn_t               lsn = 0;
 230
 231        xfs_ilock(ip, XFS_ILOCK_SHARED);
 232        if (xfs_ipincount(ip))
 233                lsn = ip->i_itemp->ili_last_lsn;
 234        xfs_iunlock(ip, XFS_ILOCK_SHARED);
 235
 236        if (!lsn)
 237                return 0;
 238        return _xfs_log_force_lsn(mp, lsn, XFS_LOG_SYNC, NULL);
 239}
 240
 241const struct export_operations xfs_export_operations = {
 242        .encode_fh              = xfs_fs_encode_fh,
 243        .fh_to_dentry           = xfs_fs_fh_to_dentry,
 244        .fh_to_parent           = xfs_fs_fh_to_parent,
 245        .get_parent             = xfs_fs_get_parent,
 246        .commit_metadata        = xfs_fs_nfs_commit_metadata,
 247};
 248
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