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_format.h"
  20 #include "xfs_log_format.h"
  21 #include "xfs_trans_resv.h"
  22 #include "xfs_sb.h"
  23 #include "xfs_ag.h"
  24 #include "xfs_mount.h"
  25 #include "xfs_da_format.h"
  26 #include "xfs_dir2.h"
  27 #include "xfs_export.h"
  28 #include "xfs_inode.h"
  29 #include "xfs_trans.h"
  30 #include "xfs_inode_item.h"
  31 #include "xfs_trace.h"
  32 #include "xfs_icache.h"
  33 #include "xfs_log.h"
  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 FILEID_INVALID;
  53 }
  54
  55 STATIC int
  56 xfs_fs_encode_fh(
  57         struct inode    *inode,
  58         __u32           *fh,
  59         int             *max_len,
  60         struct inode    *parent)
  61 {
  62         struct fid              *fid = (struct fid *)fh;
  63         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fh;
  64         int                     fileid_type;
  65         int                     len;
  66
  67         /* Directories don't need their parent encoded, they have ".." */
  68         if (!parent)
  69                 fileid_type = FILEID_INO32_GEN;
  70         else
  71                 fileid_type = FILEID_INO32_GEN_PARENT;
  72
  73         /*
  74          * If the the filesystem may contain 64bit inode numbers, we need
  75          * to use larger file handles that can represent them.
  76          *
  77          * While we only allocate inodes that do not fit into 32 bits any
  78          * large enough filesystem may contain them, thus the slightly
  79          * confusing looking conditional below.
  80          */
  81         if (!(XFS_M(inode->i_sb)->m_flags & XFS_MOUNT_SMALL_INUMS) ||
  82             (XFS_M(inode->i_sb)->m_flags & XFS_MOUNT_32BITINODES))
  83                 fileid_type |= XFS_FILEID_TYPE_64FLAG;
  84
  85         /*
  86          * Only encode if there is enough space given.  In practice
  87          * this means we can't export a filesystem with 64bit inodes
  88          * over NFSv2 with the subtree_check export option; the other
  89          * seven combinations work.  The real answer is "don't use v2".
  90          */
  91         len = xfs_fileid_length(fileid_type);
  92         if (*max_len < len) {
  93                 *max_len = len;
  94                 return FILEID_INVALID;
  95         }
  96         *max_len = len;
  97
  98         switch (fileid_type) {
  99         case FILEID_INO32_GEN_PARENT:
 100                 fid->i32.parent_ino = XFS_I(parent)->i_ino;
 101                 fid->i32.parent_gen = parent->i_generation;
 102                 /*FALLTHRU*/
 103         case FILEID_INO32_GEN:
 104                 fid->i32.ino = XFS_I(inode)->i_ino;
 105                 fid->i32.gen = inode->i_generation;
 106                 break;
 107         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 108                 fid64->parent_ino = XFS_I(parent)->i_ino;
 109                 fid64->parent_gen = parent->i_generation;
 110                 /*FALLTHRU*/
 111         case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
 112                 fid64->ino = XFS_I(inode)->i_ino;
 113                 fid64->gen = inode->i_generation;
 114                 break;
 115         }
 116
 117         return fileid_type;
 118 }
 119
 120 STATIC struct inode *
 121 xfs_nfs_get_inode(
 122         struct super_block      *sb,
 123         u64                     ino,
 124         u32                     generation)
 125  {
 126         xfs_mount_t             *mp = XFS_M(sb);
 127         xfs_inode_t             *ip;
 128         int                     error;
 129
 130         /*
 131          * NFS can sometimes send requests for ino 0.  Fail them gracefully.
 132          */
 133         if (ino == 0)
 134                 return ERR_PTR(-ESTALE);
 135
 136         /*
 137          * The XFS_IGET_UNTRUSTED means that an invalid inode number is just
 138          * fine and not an indication of a corrupted filesystem as clients can
 139          * send invalid file handles and we have to handle it gracefully..
 140          */
 141         error = xfs_iget(mp, NULL, ino, XFS_IGET_UNTRUSTED, 0, &ip);
 142         if (error) {
 143                 /*
 144                  * EINVAL means the inode cluster doesn't exist anymore.
 145                  * This implies the filehandle is stale, so we should
 146                  * translate it here.
 147                  * We don't use ESTALE directly down the chain to not
 148                  * confuse applications using bulkstat that expect EINVAL.
 149                  */
 150                 if (error == EINVAL || error == ENOENT)
 151                         error = ESTALE;
 152                 return ERR_PTR(-error);
 153         }
 154
 155         if (ip->i_d.di_gen != generation) {
 156                 IRELE(ip);
 157                 return ERR_PTR(-ESTALE);
 158         }
 159
 160         return VFS_I(ip);
 161 }
 162
 163 STATIC struct dentry *
 164 xfs_fs_fh_to_dentry(struct super_block *sb, struct fid *fid,
 165                  int fh_len, int fileid_type)
 166 {
 167         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
 168         struct inode            *inode = NULL;
 169
 170         if (fh_len < xfs_fileid_length(fileid_type))
 171                 return NULL;
 172
 173         switch (fileid_type) {
 174         case FILEID_INO32_GEN_PARENT:
 175         case FILEID_INO32_GEN:
 176                 inode = xfs_nfs_get_inode(sb, fid->i32.ino, fid->i32.gen);
 177                 break;
 178         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 179         case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
 180                 inode = xfs_nfs_get_inode(sb, fid64->ino, fid64->gen);
 181                 break;
 182         }
 183
 184         return d_obtain_alias(inode);
 185 }
 186
 187 STATIC struct dentry *
 188 xfs_fs_fh_to_parent(struct super_block *sb, struct fid *fid,
 189                  int fh_len, int fileid_type)
 190 {
 191         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
 192         struct inode            *inode = NULL;
 193
 194         if (fh_len < xfs_fileid_length(fileid_type))
 195                 return NULL;
 196
 197         switch (fileid_type) {
 198         case FILEID_INO32_GEN_PARENT:
 199                 inode = xfs_nfs_get_inode(sb, fid->i32.parent_ino,
 200                                               fid->i32.parent_gen);
 201                 break;
 202         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 203                 inode = xfs_nfs_get_inode(sb, fid64->parent_ino,
 204                                               fid64->parent_gen);
 205                 break;
 206         }
 207
 208         return d_obtain_alias(inode);
 209 }
 210
 211 STATIC struct dentry *
 212 xfs_fs_get_parent(
 213         struct dentry           *child)
 214 {
 215         int                     error;
 216         struct xfs_inode        *cip;
 217
 218         error = xfs_lookup(XFS_I(child->d_inode), &xfs_name_dotdot, &cip, NULL);
 219         if (unlikely(error))
 220                 return ERR_PTR(-error);
 221
 222         return d_obtain_alias(VFS_I(cip));
 223 }
 224
 225 STATIC int
 226 xfs_fs_nfs_commit_metadata(
 227         struct inode            *inode)
 228 {
 229         struct xfs_inode        *ip = XFS_I(inode);
 230         struct xfs_mount        *mp = ip->i_mount;
 231         xfs_lsn_t               lsn = 0;
 232
 233         xfs_ilock(ip, XFS_ILOCK_SHARED);
 234         if (xfs_ipincount(ip))
 235                 lsn = ip->i_itemp->ili_last_lsn;
 236         xfs_iunlock(ip, XFS_ILOCK_SHARED);
 237
 238         if (!lsn)
 239                 return 0;
 240         return -_xfs_log_force_lsn(mp, lsn, XFS_LOG_SYNC, NULL);
 241 }
 242
 243 const struct export_operations xfs_export_operations = {
 244         .encode_fh              = xfs_fs_encode_fh,
 245         .fh_to_dentry           = xfs_fs_fh_to_dentry,
 246         .fh_to_parent           = xfs_fs_fh_to_parent,
 247         .get_parent             = xfs_fs_get_parent,
 248         .commit_metadata        = xfs_fs_nfs_commit_metadata,
 249 };