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 #include "xfs_vfsops.h"
  33
  34 /*
  35  * Note that we only accept fileids which are long enough rather than allow
  36  * the parent generation number to default to zero.  XFS considers zero a
  37  * valid generation number not an invalid/wildcard value.
  38  */
  39 static int xfs_fileid_length(int fileid_type)
  40 {
  41         switch (fileid_type) {
  42         case FILEID_INO32_GEN:
  43                 return 2;
  44         case FILEID_INO32_GEN_PARENT:
  45                 return 4;
  46         case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
  47                 return 3;
  48         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
  49                 return 6;
  50         }
  51         return 255; /* invalid */
  52 }
  53
  54 STATIC int
  55 xfs_fs_encode_fh(
  56         struct dentry           *dentry,
  57         __u32                   *fh,
  58         int                     *max_len,
  59         int                     connectable)
  60 {
  61         struct fid              *fid = (struct fid *)fh;
  62         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fh;
  63         struct inode            *inode = dentry->d_inode;
  64         int                     fileid_type;
  65         int                     len;
  66
  67         /* Directories don't need their parent encoded, they have ".." */
  68         if (S_ISDIR(inode->i_mode) || !connectable)
  69                 fileid_type = FILEID_INO32_GEN;
  70         else
  71                 fileid_type = FILEID_INO32_GEN_PARENT;
  72
  73         /* filesystem may contain 64bit inode numbers */
  74         if (!(XFS_M(inode->i_sb)->m_flags & XFS_MOUNT_SMALL_INUMS))
  75                 fileid_type |= XFS_FILEID_TYPE_64FLAG;
  76
  77         /*
  78          * Only encode if there is enough space given.  In practice
  79          * this means we can't export a filesystem with 64bit inodes
  80          * over NFSv2 with the subtree_check export option; the other
  81          * seven combinations work.  The real answer is "don't use v2".
  82          */
  83         len = xfs_fileid_length(fileid_type);
  84         if (*max_len < len)
  85                 return 255;
  86         *max_len = len;
  87
  88         switch (fileid_type) {
  89         case FILEID_INO32_GEN_PARENT:
  90                 spin_lock(&dentry->d_lock);
  91                 fid->i32.parent_ino = dentry->d_parent->d_inode->i_ino;
  92                 fid->i32.parent_gen = dentry->d_parent->d_inode->i_generation;
  93                 spin_unlock(&dentry->d_lock);
  94                 /*FALLTHRU*/
  95         case FILEID_INO32_GEN:
  96                 fid->i32.ino = inode->i_ino;
  97                 fid->i32.gen = inode->i_generation;
  98                 break;
  99         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 100                 spin_lock(&dentry->d_lock);
 101                 fid64->parent_ino = dentry->d_parent->d_inode->i_ino;
 102                 fid64->parent_gen = dentry->d_parent->d_inode->i_generation;
 103                 spin_unlock(&dentry->d_lock);
 104                 /*FALLTHRU*/
 105         case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
 106                 fid64->ino = inode->i_ino;
 107                 fid64->gen = inode->i_generation;
 108                 break;
 109         }
 110
 111         return fileid_type;
 112 }
 113
 114 STATIC struct inode *
 115 xfs_nfs_get_inode(
 116         struct super_block      *sb,
 117         u64                     ino,
 118         u32                     generation)
 119  {
 120         xfs_mount_t             *mp = XFS_M(sb);
 121         xfs_inode_t             *ip;
 122         int                     error;
 123
 124         /*
 125          * NFS can sometimes send requests for ino 0.  Fail them gracefully.
 126          */
 127         if (ino == 0)
 128                 return ERR_PTR(-ESTALE);
 129
 130         error = xfs_iget(mp, NULL, ino, 0, XFS_ILOCK_SHARED, &ip, 0);
 131         if (error)
 132                 return ERR_PTR(-error);
 133         if (!ip)
 134                 return ERR_PTR(-EIO);
 135
 136         if (ip->i_d.di_gen != generation) {
 137                 xfs_iput_new(ip, XFS_ILOCK_SHARED);
 138                 return ERR_PTR(-ENOENT);
 139         }
 140
 141         xfs_iunlock(ip, XFS_ILOCK_SHARED);
 142         return VFS_I(ip);
 143 }
 144
 145 STATIC struct dentry *
 146 xfs_fs_fh_to_dentry(struct super_block *sb, struct fid *fid,
 147                  int fh_len, int fileid_type)
 148 {
 149         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
 150         struct inode            *inode = NULL;
 151
 152         if (fh_len < xfs_fileid_length(fileid_type))
 153                 return NULL;
 154
 155         switch (fileid_type) {
 156         case FILEID_INO32_GEN_PARENT:
 157         case FILEID_INO32_GEN:
 158                 inode = xfs_nfs_get_inode(sb, fid->i32.ino, fid->i32.gen);
 159                 break;
 160         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 161         case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
 162                 inode = xfs_nfs_get_inode(sb, fid64->ino, fid64->gen);
 163                 break;
 164         }
 165
 166         return d_obtain_alias(inode);
 167 }
 168
 169 STATIC struct dentry *
 170 xfs_fs_fh_to_parent(struct super_block *sb, struct fid *fid,
 171                  int fh_len, int fileid_type)
 172 {
 173         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
 174         struct inode            *inode = NULL;
 175
 176         switch (fileid_type) {
 177         case FILEID_INO32_GEN_PARENT:
 178                 inode = xfs_nfs_get_inode(sb, fid->i32.parent_ino,
 179                                               fid->i32.parent_gen);
 180                 break;
 181         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 182                 inode = xfs_nfs_get_inode(sb, fid64->parent_ino,
 183                                               fid64->parent_gen);
 184                 break;
 185         }
 186
 187         return d_obtain_alias(inode);
 188 }
 189
 190 STATIC struct dentry *
 191 xfs_fs_get_parent(
 192         struct dentry           *child)
 193 {
 194         int                     error;
 195         struct xfs_inode        *cip;
 196
 197         error = xfs_lookup(XFS_I(child->d_inode), &xfs_name_dotdot, &cip, NULL);
 198         if (unlikely(error))
 199                 return ERR_PTR(-error);
 200
 201         return d_obtain_alias(VFS_I(cip));
 202 }
 203
 204 const struct export_operations xfs_export_operations = {
 205         .encode_fh              = xfs_fs_encode_fh,
 206         .fh_to_dentry           = xfs_fs_fh_to_dentry,
 207         .fh_to_parent           = xfs_fs_fh_to_parent,
 208         .get_parent             = xfs_fs_get_parent,
 209 };