fs/xfs/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_log.h"
  21 #include "xfs_trans.h"
  22 #include "xfs_sb.h"
  23 #include "xfs_ag.h"
  24 #include "xfs_dir2.h"
  25 #include "xfs_mount.h"
  26 #include "xfs_export.h"
  27 #include "xfs_vnodeops.h"
  28 #include "xfs_bmap_btree.h"
  29 #include "xfs_inode.h"
  30 #include "xfs_inode_item.h"
  31 #include "xfs_trace.h"
  32 #include "xfs_icache.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 FILEID_INVALID;
  52 }
  53
  54 STATIC int
  55 xfs_fs_encode_fh(
  56         struct inode    *inode,
  57         __u32           *fh,
  58         int             *max_len,
  59         struct inode    *parent)
  60 {
  61         struct fid              *fid = (struct fid *)fh;
  62         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fh;
  63         int                     fileid_type;
  64         int                     len;
  65
  66         /* Directories don't need their parent encoded, they have ".." */
  67         if (!parent)
  68                 fileid_type = FILEID_INO32_GEN;
  69         else
  70                 fileid_type = FILEID_INO32_GEN_PARENT;
  71
  72         /*
  73          * If the the filesystem may contain 64bit inode numbers, we need
  74          * to use larger file handles that can represent them.
  75          *
  76          * While we only allocate inodes that do not fit into 32 bits any
  77          * large enough filesystem may contain them, thus the slightly
  78          * confusing looking conditional below.
  79          */
  80         if (!(XFS_M(inode->i_sb)->m_flags & XFS_MOUNT_SMALL_INUMS) ||
  81             (XFS_M(inode->i_sb)->m_flags & XFS_MOUNT_32BITINODES))
  82                 fileid_type |= XFS_FILEID_TYPE_64FLAG;
  83
  84         /*
  85          * Only encode if there is enough space given.  In practice
  86          * this means we can't export a filesystem with 64bit inodes
  87          * over NFSv2 with the subtree_check export option; the other
  88          * seven combinations work.  The real answer is "don't use v2".
  89          */
  90         len = xfs_fileid_length(fileid_type);
  91         if (*max_len < len) {
  92                 *max_len = len;
  93                 return FILEID_INVALID;
  94         }
  95         *max_len = len;
  96
  97         switch (fileid_type) {
  98         case FILEID_INO32_GEN_PARENT:
  99                 fid->i32.parent_ino = XFS_I(parent)->i_ino;
 100                 fid->i32.parent_gen = parent->i_generation;
 101                 /*FALLTHRU*/
 102         case FILEID_INO32_GEN:
 103                 fid->i32.ino = XFS_I(inode)->i_ino;
 104                 fid->i32.gen = inode->i_generation;
 105                 break;
 106         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 107                 fid64->parent_ino = XFS_I(parent)->i_ino;
 108                 fid64->parent_gen = parent->i_generation;
 109                 /*FALLTHRU*/
 110         case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
 111                 fid64->ino = XFS_I(inode)->i_ino;
 112                 fid64->gen = inode->i_generation;
 113                 break;
 114         }
 115
 116         return fileid_type;
 117 }
 118
 119 STATIC struct inode *
 120 xfs_nfs_get_inode(
 121         struct super_block      *sb,
 122         u64                     ino,
 123         u32                     generation)
 124  {
 125         xfs_mount_t             *mp = XFS_M(sb);
 126         xfs_inode_t             *ip;
 127         int                     error;
 128
 129         /*
 130          * NFS can sometimes send requests for ino 0.  Fail them gracefully.
 131          */
 132         if (ino == 0)
 133                 return ERR_PTR(-ESTALE);
 134
 135         /*
 136          * The XFS_IGET_UNTRUSTED means that an invalid inode number is just
 137          * fine and not an indication of a corrupted filesystem as clients can
 138          * send invalid file handles and we have to handle it gracefully..
 139          */
 140         error = xfs_iget(mp, NULL, ino, XFS_IGET_UNTRUSTED, 0, &ip);
 141         if (error) {
 142                 /*
 143                  * EINVAL means the inode cluster doesn't exist anymore.
 144                  * This implies the filehandle is stale, so we should
 145                  * translate it here.
 146                  * We don't use ESTALE directly down the chain to not
 147                  * confuse applications using bulkstat that expect EINVAL.
 148                  */
 149                 if (error == EINVAL || error == ENOENT)
 150                         error = ESTALE;
 151                 return ERR_PTR(-error);
 152         }
 153
 154         if (ip->i_d.di_gen != generation) {
 155                 IRELE(ip);
 156                 return ERR_PTR(-ESTALE);
 157         }
 158
 159         return VFS_I(ip);
 160 }
 161
 162 STATIC struct dentry *
 163 xfs_fs_fh_to_dentry(struct super_block *sb, struct fid *fid,
 164                  int fh_len, int fileid_type)
 165 {
 166         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
 167         struct inode            *inode = NULL;
 168
 169         if (fh_len < xfs_fileid_length(fileid_type))
 170                 return NULL;
 171
 172         switch (fileid_type) {
 173         case FILEID_INO32_GEN_PARENT:
 174         case FILEID_INO32_GEN:
 175                 inode = xfs_nfs_get_inode(sb, fid->i32.ino, fid->i32.gen);
 176                 break;
 177         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 178         case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
 179                 inode = xfs_nfs_get_inode(sb, fid64->ino, fid64->gen);
 180                 break;
 181         }
 182
 183         return d_obtain_alias(inode);
 184 }
 185
 186 STATIC struct dentry *
 187 xfs_fs_fh_to_parent(struct super_block *sb, struct fid *fid,
 188                  int fh_len, int fileid_type)
 189 {
 190         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
 191         struct inode            *inode = NULL;
 192
 193         if (fh_len < xfs_fileid_length(fileid_type))
 194                 return NULL;
 195
 196         switch (fileid_type) {
 197         case FILEID_INO32_GEN_PARENT:
 198                 inode = xfs_nfs_get_inode(sb, fid->i32.parent_ino,
 199                                               fid->i32.parent_gen);
 200                 break;
 201         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 202                 inode = xfs_nfs_get_inode(sb, fid64->parent_ino,
 203                                               fid64->parent_gen);
 204                 break;
 205         }
 206
 207         return d_obtain_alias(inode);
 208 }
 209
 210 STATIC struct dentry *
 211 xfs_fs_get_parent(
 212         struct dentry           *child)
 213 {
 214         int                     error;
 215         struct xfs_inode        *cip;
 216
 217         error = xfs_lookup(XFS_I(child->d_inode), &xfs_name_dotdot, &cip, NULL);
 218         if (unlikely(error))
 219                 return ERR_PTR(-error);
 220
 221         return d_obtain_alias(VFS_I(cip));
 222 }
 223
 224 STATIC int
 225 xfs_fs_nfs_commit_metadata(
 226         struct inode            *inode)
 227 {
 228         struct xfs_inode        *ip = XFS_I(inode);
 229         struct xfs_mount        *mp = ip->i_mount;
 230         xfs_lsn_t               lsn = 0;
 231
 232         xfs_ilock(ip, XFS_ILOCK_SHARED);
 233         if (xfs_ipincount(ip))
 234                 lsn = ip->i_itemp->ili_last_lsn;
 235         xfs_iunlock(ip, XFS_ILOCK_SHARED);
 236
 237         if (!lsn)
 238                 return 0;
 239         return _xfs_log_force_lsn(mp, lsn, XFS_LOG_SYNC, NULL);
 240 }
 241
 242 const struct export_operations xfs_export_operations = {
 243         .encode_fh              = xfs_fs_encode_fh,
 244         .fh_to_dentry           = xfs_fs_fh_to_dentry,
 245         .fh_to_parent           = xfs_fs_fh_to_parent,
 246         .get_parent             = xfs_fs_get_parent,
 247         .commit_metadata        = xfs_fs_nfs_commit_metadata,
 248 };