fs/xfs/linux-2.6/xfs_export.c

   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_dmapi.h"
  21 #include "xfs_log.h"
  22 #include "xfs_trans.h"
  23 #include "xfs_sb.h"
  24 #include "xfs_dir.h"
  25 #include "xfs_mount.h"
  26 #include "xfs_export.h"
  27
  28 STATIC struct dentry dotdot = { .d_name.name = "..", .d_name.len = 2, };
  29
  30 /*
  31  * XFS encodes and decodes the fileid portion of NFS filehandles
  32  * itself instead of letting the generic NFS code do it.  This
  33  * allows filesystems with 64 bit inode numbers to be exported.
  34  *
  35  * Note that a side effect is that xfs_vget() won't be passed a
  36  * zero inode/generation pair under normal circumstances.  As
  37  * however a malicious client could send us such data, the check
  38  * remains in that code.
  39  */
  40
  41 STATIC struct dentry *
  42 xfs_fs_decode_fh(
  43         struct super_block      *sb,
  44         __u32                   *fh,
  45         int                     fh_len,
  46         int                     fileid_type,
  47         int (*acceptable)(
  48                 void            *context,
  49                 struct dentry   *de),
  50         void                    *context)
  51 {
  52         xfs_fid2_t              ifid;
  53         xfs_fid2_t              pfid;
  54         void                    *parent = NULL;
  55         int                     is64 = 0;
  56         __u32                   *p = fh;
  57
  58 #if XFS_BIG_INUMS
  59         is64 = (fileid_type & XFS_FILEID_TYPE_64FLAG);
  60         fileid_type &= ~XFS_FILEID_TYPE_64FLAG;
  61 #endif
  62
  63         /*
  64          * Note that we only accept fileids which are long enough
  65          * rather than allow the parent generation number to default
  66          * to zero.  XFS considers zero a valid generation number not
  67          * an invalid/wildcard value.  There's little point printk'ing
  68          * a warning here as we don't have the client information
  69          * which would make such a warning useful.
  70          */
  71         if (fileid_type > 2 ||
  72             fh_len < xfs_fileid_length((fileid_type == 2), is64))
  73                 return NULL;
  74
  75         p = xfs_fileid_decode_fid2(p, &ifid, is64);
  76
  77         if (fileid_type == 2) {
  78                 p = xfs_fileid_decode_fid2(p, &pfid, is64);
  79                 parent = &pfid;
  80         }
  81
  82         fh = (__u32 *)&ifid;
  83         return sb->s_export_op->find_exported_dentry(sb, fh, parent, acceptable, context);
  84 }
  85
  86
  87 STATIC int
  88 xfs_fs_encode_fh(
  89         struct dentry           *dentry,
  90         __u32                   *fh,
  91         int                     *max_len,
  92         int                     connectable)
  93 {
  94         struct inode            *inode = dentry->d_inode;
  95         int                     type = 1;
  96         __u32                   *p = fh;
  97         int                     len;
  98         int                     is64 = 0;
  99 #if XFS_BIG_INUMS
 100         vfs_t                   *vfs = vfs_from_sb(inode->i_sb);
 101
 102         if (!(vfs->vfs_flag & VFS_32BITINODES)) {
 103                 /* filesystem may contain 64bit inode numbers */
 104                 is64 = XFS_FILEID_TYPE_64FLAG;
 105         }
 106 #endif
 107
 108         /* Directories don't need their parent encoded, they have ".." */
 109         if (S_ISDIR(inode->i_mode))
 110             connectable = 0;
 111
 112         /*
 113          * Only encode if there is enough space given.  In practice
 114          * this means we can't export a filesystem with 64bit inodes
 115          * over NFSv2 with the subtree_check export option; the other
 116          * seven combinations work.  The real answer is "don't use v2".
 117          */
 118         len = xfs_fileid_length(connectable, is64);
 119         if (*max_len < len)
 120                 return 255;
 121         *max_len = len;
 122
 123         p = xfs_fileid_encode_inode(p, inode, is64);
 124         if (connectable) {
 125                 spin_lock(&dentry->d_lock);
 126                 p = xfs_fileid_encode_inode(p, dentry->d_parent->d_inode, is64);
 127                 spin_unlock(&dentry->d_lock);
 128                 type = 2;
 129         }
 130         BUG_ON((p - fh) != len);
 131         return type | is64;
 132 }
 133
 134 STATIC struct dentry *
 135 xfs_fs_get_dentry(
 136         struct super_block      *sb,
 137         void                    *data)
 138 {
 139         vnode_t                 *vp;
 140         struct inode            *inode;
 141         struct dentry           *result;
 142         vfs_t                   *vfsp = vfs_from_sb(sb);
 143         int                     error;
 144
 145         VFS_VGET(vfsp, &vp, (fid_t *)data, error);
 146         if (error || vp == NULL)
 147                 return ERR_PTR(-ESTALE) ;
 148
 149         inode = vn_to_inode(vp);
 150         result = d_alloc_anon(inode);
 151         if (!result) {
 152                 iput(inode);
 153                 return ERR_PTR(-ENOMEM);
 154         }
 155         return result;
 156 }
 157
 158 STATIC struct dentry *
 159 xfs_fs_get_parent(
 160         struct dentry           *child)
 161 {
 162         int                     error;
 163         vnode_t                 *vp, *cvp;
 164         struct dentry           *parent;
 165
 166         cvp = NULL;
 167         vp = vn_from_inode(child->d_inode);
 168         VOP_LOOKUP(vp, &dotdot, &cvp, 0, NULL, NULL, error);
 169         if (unlikely(error))
 170                 return ERR_PTR(-error);
 171
 172         parent = d_alloc_anon(vn_to_inode(cvp));
 173         if (unlikely(!parent)) {
 174                 VN_RELE(cvp);
 175                 return ERR_PTR(-ENOMEM);
 176         }
 177         return parent;
 178 }
 179
 180 struct export_operations xfs_export_operations = {
 181         .decode_fh              = xfs_fs_decode_fh,
 182         .encode_fh              = xfs_fs_encode_fh,
 183         .get_parent             = xfs_fs_get_parent,
 184         .get_dentry             = xfs_fs_get_dentry,
 185 };