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