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  * Note that we only accept fileids which are long enough rather than allow
  37  * the parent generation number to default to zero.  XFS considers zero a
  38  * valid generation number not an invalid/wildcard value.
  39  */
  40 static int xfs_fileid_length(int fileid_type)
  41 {
  42         switch (fileid_type) {
  43         case FILEID_INO32_GEN:
  44                 return 2;
  45         case FILEID_INO32_GEN_PARENT:
  46                 return 4;
  47         case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
  48                 return 3;
  49         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
  50                 return 6;
  51         }
  52         return 255; /* invalid */
  53 }
  54
  55 STATIC int
  56 xfs_fs_encode_fh(
  57         struct dentry           *dentry,
  58         __u32                   *fh,
  59         int                     *max_len,
  60         int                     connectable)
  61 {
  62         struct fid              *fid = (struct fid *)fh;
  63         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fh;
  64         struct inode            *inode = dentry->d_inode;
  65         int                     fileid_type;
  66         int                     len;
  67
  68         /* Directories don't need their parent encoded, they have ".." */
  69         if (S_ISDIR(inode->i_mode))
  70                 fileid_type = FILEID_INO32_GEN;
  71         else
  72                 fileid_type = FILEID_INO32_GEN_PARENT;
  73
  74         /* filesystem may contain 64bit inode numbers */
  75         if (!(XFS_M(inode->i_sb)->m_flags & XFS_MOUNT_SMALL_INUMS))
  76                 fileid_type |= XFS_FILEID_TYPE_64FLAG;
  77
  78         /*
  79          * Only encode if there is enough space given.  In practice
  80          * this means we can't export a filesystem with 64bit inodes
  81          * over NFSv2 with the subtree_check export option; the other
  82          * seven combinations work.  The real answer is "don't use v2".
  83          */
  84         len = xfs_fileid_length(fileid_type);
  85         if (*max_len < len)
  86                 return 255;
  87         *max_len = len;
  88
  89         switch (fileid_type) {
  90         case FILEID_INO32_GEN_PARENT:
  91                 spin_lock(&dentry->d_lock);
  92                 fid->i32.parent_ino = dentry->d_parent->d_inode->i_ino;
  93                 fid->i32.parent_gen = dentry->d_parent->d_inode->i_generation;
  94                 spin_unlock(&dentry->d_lock);
  95                 /*FALLTHRU*/
  96         case FILEID_INO32_GEN:
  97                 fid->i32.ino = inode->i_ino;
  98                 fid->i32.gen = inode->i_generation;
  99                 break;
 100         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 101                 spin_lock(&dentry->d_lock);
 102                 fid64->parent_ino = dentry->d_parent->d_inode->i_ino;
 103                 fid64->parent_gen = dentry->d_parent->d_inode->i_generation;
 104                 spin_unlock(&dentry->d_lock);
 105                 /*FALLTHRU*/
 106         case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
 107                 fid64->ino = inode->i_ino;
 108                 fid64->gen = inode->i_generation;
 109                 break;
 110         }
 111
 112         return fileid_type;
 113 }
 114
 115 STATIC struct inode *
 116 xfs_nfs_get_inode(
 117         struct super_block      *sb,
 118         u64                     ino,
 119         u32                     generation)
 120  {
 121         xfs_mount_t             *mp = XFS_M(sb);
 122         xfs_inode_t             *ip;
 123         int                     error;
 124
 125         /*
 126          * NFS can sometimes send requests for ino 0.  Fail them gracefully.
 127          */
 128         if (ino == 0)
 129                 return ERR_PTR(-ESTALE);
 130
 131         error = xfs_iget(mp, NULL, ino, 0, XFS_ILOCK_SHARED, &ip, 0);
 132         if (error)
 133                 return ERR_PTR(-error);
 134         if (!ip)
 135                 return ERR_PTR(-EIO);
 136
 137         if (!ip->i_d.di_mode || ip->i_d.di_gen != generation) {
 138                 xfs_iput_new(ip, XFS_ILOCK_SHARED);
 139                 return ERR_PTR(-ENOENT);
 140         }
 141
 142         xfs_iunlock(ip, XFS_ILOCK_SHARED);
 143         return ip->i_vnode;
 144 }
 145
 146 STATIC struct dentry *
 147 xfs_fs_fh_to_dentry(struct super_block *sb, struct fid *fid,
 148                  int fh_len, int fileid_type)
 149 {
 150         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
 151         struct inode            *inode = NULL;
 152         struct dentry           *result;
 153
 154         if (fh_len < xfs_fileid_length(fileid_type))
 155                 return NULL;
 156
 157         switch (fileid_type) {
 158         case FILEID_INO32_GEN_PARENT:
 159         case FILEID_INO32_GEN:
 160                 inode = xfs_nfs_get_inode(sb, fid->i32.ino, fid->i32.gen);
 161                 break;
 162         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 163         case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
 164                 inode = xfs_nfs_get_inode(sb, fid64->ino, fid64->gen);
 165                 break;
 166         }
 167
 168         if (!inode)
 169                 return NULL;
 170         if (IS_ERR(inode))
 171                 return ERR_PTR(PTR_ERR(inode));
 172         result = d_alloc_anon(inode);
 173         if (!result) {
 174                 iput(inode);
 175                 return ERR_PTR(-ENOMEM);
 176         }
 177         return result;
 178 }
 179
 180 STATIC struct dentry *
 181 xfs_fs_fh_to_parent(struct super_block *sb, struct fid *fid,
 182                  int fh_len, int fileid_type)
 183 {
 184         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
 185         struct inode            *inode = NULL;
 186         struct dentry           *result;
 187
 188         switch (fileid_type) {
 189         case FILEID_INO32_GEN_PARENT:
 190                 inode = xfs_nfs_get_inode(sb, fid->i32.parent_ino,
 191                                               fid->i32.parent_gen);
 192                 break;
 193         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 194                 inode = xfs_nfs_get_inode(sb, fid64->parent_ino,
 195                                               fid64->parent_gen);
 196                 break;
 197         }
 198
 199         if (!inode)
 200                 return NULL;
 201         if (IS_ERR(inode))
 202                 return ERR_PTR(PTR_ERR(inode));
 203         result = d_alloc_anon(inode);
 204         if (!result) {
 205                 iput(inode);
 206                 return ERR_PTR(-ENOMEM);
 207         }
 208         return result;
 209 }
 210
 211 STATIC struct dentry *
 212 xfs_fs_get_parent(
 213         struct dentry           *child)
 214 {
 215         int                     error;
 216         bhv_vnode_t             *cvp;
 217         struct dentry           *parent;
 218
 219         cvp = NULL;
 220         error = xfs_lookup(XFS_I(child->d_inode), &dotdot, &cvp);
 221         if (unlikely(error))
 222                 return ERR_PTR(-error);
 223
 224         parent = d_alloc_anon(vn_to_inode(cvp));
 225         if (unlikely(!parent)) {
 226                 VN_RELE(cvp);
 227                 return ERR_PTR(-ENOMEM);
 228         }
 229         return parent;
 230 }
 231
 232 const struct export_operations xfs_export_operations = {
 233         .encode_fh              = xfs_fs_encode_fh,
 234         .fh_to_dentry           = xfs_fs_fh_to_dentry,
 235         .fh_to_parent           = xfs_fs_fh_to_parent,
 236         .get_parent             = xfs_fs_get_parent,
 237 };