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_inum.h"
  21 #include "xfs_log.h"
  22 #include "xfs_trans.h"
  23 #include "xfs_sb.h"
  24 #include "xfs_ag.h"
  25 #include "xfs_dmapi.h"
  26 #include "xfs_mount.h"
  27 #include "xfs_export.h"
  28 #include "xfs_vnodeops.h"
  29 #include "xfs_bmap_btree.h"
  30 #include "xfs_inode.h"
  31
  32 static struct dentry dotdot = { .d_name.name = "..", .d_name.len = 2, };
  33
  34 /*
  35  * XFS encodes and decodes the fileid portion of NFS filehandles
  36  * itself instead of letting the generic NFS code do it.  This
  37  * allows filesystems with 64 bit inode numbers to be exported.
  38  *
  39  * Note that a side effect is that xfs_vget() won't be passed a
  40  * zero inode/generation pair under normal circumstances.  As
  41  * however a malicious client could send us such data, the check
  42  * remains in that code.
  43  */
  44
  45 STATIC struct dentry *
  46 xfs_fs_decode_fh(
  47         struct super_block      *sb,
  48         __u32                   *fh,
  49         int                     fh_len,
  50         int                     fileid_type,
  51         int (*acceptable)(
  52                 void            *context,
  53                 struct dentry   *de),
  54         void                    *context)
  55 {
  56         xfs_fid2_t              ifid;
  57         xfs_fid2_t              pfid;
  58         void                    *parent = NULL;
  59         int                     is64 = 0;
  60         __u32                   *p = fh;
  61
  62 #if XFS_BIG_INUMS
  63         is64 = (fileid_type & XFS_FILEID_TYPE_64FLAG);
  64         fileid_type &= ~XFS_FILEID_TYPE_64FLAG;
  65 #endif
  66
  67         /*
  68          * Note that we only accept fileids which are long enough
  69          * rather than allow the parent generation number to default
  70          * to zero.  XFS considers zero a valid generation number not
  71          * an invalid/wildcard value.  There's little point printk'ing
  72          * a warning here as we don't have the client information
  73          * which would make such a warning useful.
  74          */
  75         if (fileid_type > 2 ||
  76             fh_len < xfs_fileid_length((fileid_type == 2), is64))
  77                 return NULL;
  78
  79         p = xfs_fileid_decode_fid2(p, &ifid, is64);
  80
  81         if (fileid_type == 2) {
  82                 p = xfs_fileid_decode_fid2(p, &pfid, is64);
  83                 parent = &pfid;
  84         }
  85
  86         fh = (__u32 *)&ifid;
  87         return sb->s_export_op->find_exported_dentry(sb, fh, parent, acceptable, context);
  88 }
  89
  90
  91 STATIC int
  92 xfs_fs_encode_fh(
  93         struct dentry           *dentry,
  94         __u32                   *fh,
  95         int                     *max_len,
  96         int                     connectable)
  97 {
  98         struct inode            *inode = dentry->d_inode;
  99         int                     type = 1;
 100         __u32                   *p = fh;
 101         int                     len;
 102         int                     is64 = 0;
 103 #if XFS_BIG_INUMS
 104         bhv_vfs_t               *vfs = vfs_from_sb(inode->i_sb);
 105
 106         if (!(vfs->vfs_flag & VFS_32BITINODES)) {
 107                 /* filesystem may contain 64bit inode numbers */
 108                 is64 = XFS_FILEID_TYPE_64FLAG;
 109         }
 110 #endif
 111
 112         /* Directories don't need their parent encoded, they have ".." */
 113         if (S_ISDIR(inode->i_mode))
 114             connectable = 0;
 115
 116         /*
 117          * Only encode if there is enough space given.  In practice
 118          * this means we can't export a filesystem with 64bit inodes
 119          * over NFSv2 with the subtree_check export option; the other
 120          * seven combinations work.  The real answer is "don't use v2".
 121          */
 122         len = xfs_fileid_length(connectable, is64);
 123         if (*max_len < len)
 124                 return 255;
 125         *max_len = len;
 126
 127         p = xfs_fileid_encode_inode(p, inode, is64);
 128         if (connectable) {
 129                 spin_lock(&dentry->d_lock);
 130                 p = xfs_fileid_encode_inode(p, dentry->d_parent->d_inode, is64);
 131                 spin_unlock(&dentry->d_lock);
 132                 type = 2;
 133         }
 134         BUG_ON((p - fh) != len);
 135         return type | is64;
 136 }
 137
 138 STATIC struct dentry *
 139 xfs_fs_get_dentry(
 140         struct super_block      *sb,
 141         void                    *data)
 142 {
 143         bhv_vnode_t             *vp;
 144         struct inode            *inode;
 145         struct dentry           *result;
 146         bhv_vfs_t               *vfsp = vfs_from_sb(sb);
 147         int                     error;
 148
 149         error = bhv_vfs_vget(vfsp, &vp, (fid_t *)data);
 150         if (error || vp == NULL)
 151                 return ERR_PTR(-ESTALE) ;
 152
 153         inode = vn_to_inode(vp);
 154         result = d_alloc_anon(inode);
 155         if (!result) {
 156                 iput(inode);
 157                 return ERR_PTR(-ENOMEM);
 158         }
 159         return result;
 160 }
 161
 162 STATIC struct dentry *
 163 xfs_fs_get_parent(
 164         struct dentry           *child)
 165 {
 166         int                     error;
 167         bhv_vnode_t             *cvp;
 168         struct dentry           *parent;
 169
 170         cvp = NULL;
 171         error = xfs_lookup(XFS_I(child->d_inode), &dotdot, &cvp);
 172         if (unlikely(error))
 173                 return ERR_PTR(-error);
 174
 175         parent = d_alloc_anon(vn_to_inode(cvp));
 176         if (unlikely(!parent)) {
 177                 VN_RELE(cvp);
 178                 return ERR_PTR(-ENOMEM);
 179         }
 180         return parent;
 181 }
 182
 183 struct export_operations xfs_export_operations = {
 184         .decode_fh              = xfs_fs_decode_fh,
 185         .encode_fh              = xfs_fs_encode_fh,
 186         .get_parent             = xfs_fs_get_parent,
 187         .get_dentry             = xfs_fs_get_dentry,
 188 };