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