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_dir2.h"
  26 #include "xfs_dmapi.h"
  27 #include "xfs_mount.h"
  28 #include "xfs_export.h"
  29 #include "xfs_vnodeops.h"
  30 #include "xfs_bmap_btree.h"
  31 #include "xfs_inode.h"
  32
  33 /*
  34  * Note that we only accept fileids which are long enough rather than allow
  35  * the parent generation number to default to zero.  XFS considers zero a
  36  * valid generation number not an invalid/wildcard value.
  37  */
  38 static int xfs_fileid_length(int fileid_type)
  39 {
  40         switch (fileid_type) {
  41         case FILEID_INO32_GEN:
  42                 return 2;
  43         case FILEID_INO32_GEN_PARENT:
  44                 return 4;
  45         case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
  46                 return 3;
  47         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
  48                 return 6;
  49         }
  50         return 255; /* invalid */
  51 }
  52
  53 STATIC int
  54 xfs_fs_encode_fh(
  55         struct dentry           *dentry,
  56         __u32                   *fh,
  57         int                     *max_len,
  58         int                     connectable)
  59 {
  60         struct fid              *fid = (struct fid *)fh;
  61         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fh;
  62         struct inode            *inode = dentry->d_inode;
  63         int                     fileid_type;
  64         int                     len;
  65
  66         /* Directories don't need their parent encoded, they have ".." */
  67         if (S_ISDIR(inode->i_mode) || !connectable)
  68                 fileid_type = FILEID_INO32_GEN;
  69         else
  70                 fileid_type = FILEID_INO32_GEN_PARENT;
  71
  72         /* filesystem may contain 64bit inode numbers */
  73         if (!(XFS_M(inode->i_sb)->m_flags & XFS_MOUNT_SMALL_INUMS))
  74                 fileid_type |= XFS_FILEID_TYPE_64FLAG;
  75
  76         /*
  77          * Only encode if there is enough space given.  In practice
  78          * this means we can't export a filesystem with 64bit inodes
  79          * over NFSv2 with the subtree_check export option; the other
  80          * seven combinations work.  The real answer is "don't use v2".
  81          */
  82         len = xfs_fileid_length(fileid_type);
  83         if (*max_len < len)
  84                 return 255;
  85         *max_len = len;
  86
  87         switch (fileid_type) {
  88         case FILEID_INO32_GEN_PARENT:
  89                 spin_lock(&dentry->d_lock);
  90                 fid->i32.parent_ino = dentry->d_parent->d_inode->i_ino;
  91                 fid->i32.parent_gen = dentry->d_parent->d_inode->i_generation;
  92                 spin_unlock(&dentry->d_lock);
  93                 /*FALLTHRU*/
  94         case FILEID_INO32_GEN:
  95                 fid->i32.ino = inode->i_ino;
  96                 fid->i32.gen = inode->i_generation;
  97                 break;
  98         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
  99                 spin_lock(&dentry->d_lock);
 100                 fid64->parent_ino = dentry->d_parent->d_inode->i_ino;
 101                 fid64->parent_gen = dentry->d_parent->d_inode->i_generation;
 102                 spin_unlock(&dentry->d_lock);
 103                 /*FALLTHRU*/
 104         case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
 105                 fid64->ino = inode->i_ino;
 106                 fid64->gen = inode->i_generation;
 107                 break;
 108         }
 109
 110         return fileid_type;
 111 }
 112
 113 STATIC struct inode *
 114 xfs_nfs_get_inode(
 115         struct super_block      *sb,
 116         u64                     ino,
 117         u32                     generation)
 118  {
 119         xfs_mount_t             *mp = XFS_M(sb);
 120         xfs_inode_t             *ip;
 121         int                     error;
 122
 123         /*
 124          * NFS can sometimes send requests for ino 0.  Fail them gracefully.
 125          */
 126         if (ino == 0)
 127                 return ERR_PTR(-ESTALE);
 128
 129         error = xfs_iget(mp, NULL, ino, 0, XFS_ILOCK_SHARED, &ip, 0);
 130         if (error)
 131                 return ERR_PTR(-error);
 132         if (!ip)
 133                 return ERR_PTR(-EIO);
 134
 135         if (ip->i_d.di_gen != generation) {
 136                 xfs_iput_new(ip, XFS_ILOCK_SHARED);
 137                 return ERR_PTR(-ENOENT);
 138         }
 139
 140         xfs_iunlock(ip, XFS_ILOCK_SHARED);
 141         return VFS_I(ip);
 142 }
 143
 144 STATIC struct dentry *
 145 xfs_fs_fh_to_dentry(struct super_block *sb, struct fid *fid,
 146                  int fh_len, int fileid_type)
 147 {
 148         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
 149         struct inode            *inode = NULL;
 150
 151         if (fh_len < xfs_fileid_length(fileid_type))
 152                 return NULL;
 153
 154         switch (fileid_type) {
 155         case FILEID_INO32_GEN_PARENT:
 156         case FILEID_INO32_GEN:
 157                 inode = xfs_nfs_get_inode(sb, fid->i32.ino, fid->i32.gen);
 158                 break;
 159         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 160         case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
 161                 inode = xfs_nfs_get_inode(sb, fid64->ino, fid64->gen);
 162                 break;
 163         }
 164
 165         return d_obtain_alias(inode);
 166 }
 167
 168 STATIC struct dentry *
 169 xfs_fs_fh_to_parent(struct super_block *sb, struct fid *fid,
 170                  int fh_len, int fileid_type)
 171 {
 172         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
 173         struct inode            *inode = NULL;
 174
 175         switch (fileid_type) {
 176         case FILEID_INO32_GEN_PARENT:
 177                 inode = xfs_nfs_get_inode(sb, fid->i32.parent_ino,
 178                                               fid->i32.parent_gen);
 179                 break;
 180         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 181                 inode = xfs_nfs_get_inode(sb, fid64->parent_ino,
 182                                               fid64->parent_gen);
 183                 break;
 184         }
 185
 186         return d_obtain_alias(inode);
 187 }
 188
 189 STATIC struct dentry *
 190 xfs_fs_get_parent(
 191         struct dentry           *child)
 192 {
 193         int                     error;
 194         struct xfs_inode        *cip;
 195
 196         error = xfs_lookup(XFS_I(child->d_inode), &xfs_name_dotdot, &cip, NULL);
 197         if (unlikely(error))
 198                 return ERR_PTR(-error);
 199
 200         return d_obtain_alias(VFS_I(cip));
 201 }
 202
 203 const struct export_operations xfs_export_operations = {
 204         .encode_fh              = xfs_fs_encode_fh,
 205         .fh_to_dentry           = xfs_fs_fh_to_dentry,
 206         .fh_to_parent           = xfs_fs_fh_to_parent,
 207         .get_parent             = xfs_fs_get_parent,
 208 };