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_mount.h"
  25 #include "xfs_da_btree.h"
  26 #include "xfs_dir2_format.h"
  27 #include "xfs_dir2.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_inode_item.h"
  33 #include "xfs_trace.h"
  34 #include "xfs_icache.h"
  35
  36 /*
  37  * Note that we only accept fileids which are long enough rather than allow
  38  * the parent generation number to default to zero.  XFS considers zero a
  39  * valid generation number not an invalid/wildcard value.
  40  */
  41 static int xfs_fileid_length(int fileid_type)
  42 {
  43         switch (fileid_type) {
  44         case FILEID_INO32_GEN:
  45                 return 2;
  46         case FILEID_INO32_GEN_PARENT:
  47                 return 4;
  48         case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
  49                 return 3;
  50         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
  51                 return 6;
  52         }
  53         return FILEID_INVALID;
  54 }
  55
  56 STATIC int
  57 xfs_fs_encode_fh(
  58         struct inode    *inode,
  59         __u32           *fh,
  60         int             *max_len,
  61         struct inode    *parent)
  62 {
  63         struct fid              *fid = (struct fid *)fh;
  64         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fh;
  65         int                     fileid_type;
  66         int                     len;
  67
  68         /* Directories don't need their parent encoded, they have ".." */
  69         if (!parent)
  70                 fileid_type = FILEID_INO32_GEN;
  71         else
  72                 fileid_type = FILEID_INO32_GEN_PARENT;
  73
  74         /*
  75          * If the the filesystem may contain 64bit inode numbers, we need
  76          * to use larger file handles that can represent them.
  77          *
  78          * While we only allocate inodes that do not fit into 32 bits any
  79          * large enough filesystem may contain them, thus the slightly
  80          * confusing looking conditional below.
  81          */
  82         if (!(XFS_M(inode->i_sb)->m_flags & XFS_MOUNT_SMALL_INUMS) ||
  83             (XFS_M(inode->i_sb)->m_flags & XFS_MOUNT_32BITINODES))
  84                 fileid_type |= XFS_FILEID_TYPE_64FLAG;
  85
  86         /*
  87          * Only encode if there is enough space given.  In practice
  88          * this means we can't export a filesystem with 64bit inodes
  89          * over NFSv2 with the subtree_check export option; the other
  90          * seven combinations work.  The real answer is "don't use v2".
  91          */
  92         len = xfs_fileid_length(fileid_type);
  93         if (*max_len < len) {
  94                 *max_len = len;
  95                 return FILEID_INVALID;
  96         }
  97         *max_len = len;
  98
  99         switch (fileid_type) {
 100         case FILEID_INO32_GEN_PARENT:
 101                 fid->i32.parent_ino = XFS_I(parent)->i_ino;
 102                 fid->i32.parent_gen = parent->i_generation;
 103                 /*FALLTHRU*/
 104         case FILEID_INO32_GEN:
 105                 fid->i32.ino = XFS_I(inode)->i_ino;
 106                 fid->i32.gen = inode->i_generation;
 107                 break;
 108         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 109                 fid64->parent_ino = XFS_I(parent)->i_ino;
 110                 fid64->parent_gen = parent->i_generation;
 111                 /*FALLTHRU*/
 112         case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
 113                 fid64->ino = XFS_I(inode)->i_ino;
 114                 fid64->gen = inode->i_generation;
 115                 break;
 116         }
 117
 118         return fileid_type;
 119 }
 120
 121 STATIC struct inode *
 122 xfs_nfs_get_inode(
 123         struct super_block      *sb,
 124         u64                     ino,
 125         u32                     generation)
 126  {
 127         xfs_mount_t             *mp = XFS_M(sb);
 128         xfs_inode_t             *ip;
 129         int                     error;
 130
 131         /*
 132          * NFS can sometimes send requests for ino 0.  Fail them gracefully.
 133          */
 134         if (ino == 0)
 135                 return ERR_PTR(-ESTALE);
 136
 137         /*
 138          * The XFS_IGET_UNTRUSTED means that an invalid inode number is just
 139          * fine and not an indication of a corrupted filesystem as clients can
 140          * send invalid file handles and we have to handle it gracefully..
 141          */
 142         error = xfs_iget(mp, NULL, ino, XFS_IGET_UNTRUSTED, 0, &ip);
 143         if (error) {
 144                 /*
 145                  * EINVAL means the inode cluster doesn't exist anymore.
 146                  * This implies the filehandle is stale, so we should
 147                  * translate it here.
 148                  * We don't use ESTALE directly down the chain to not
 149                  * confuse applications using bulkstat that expect EINVAL.
 150                  */
 151                 if (error == EINVAL || error == ENOENT)
 152                         error = ESTALE;
 153                 return ERR_PTR(-error);
 154         }
 155
 156         if (ip->i_d.di_gen != generation) {
 157                 IRELE(ip);
 158                 return ERR_PTR(-ESTALE);
 159         }
 160
 161         return VFS_I(ip);
 162 }
 163
 164 STATIC struct dentry *
 165 xfs_fs_fh_to_dentry(struct super_block *sb, struct fid *fid,
 166                  int fh_len, int fileid_type)
 167 {
 168         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
 169         struct inode            *inode = NULL;
 170
 171         if (fh_len < xfs_fileid_length(fileid_type))
 172                 return NULL;
 173
 174         switch (fileid_type) {
 175         case FILEID_INO32_GEN_PARENT:
 176         case FILEID_INO32_GEN:
 177                 inode = xfs_nfs_get_inode(sb, fid->i32.ino, fid->i32.gen);
 178                 break;
 179         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 180         case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
 181                 inode = xfs_nfs_get_inode(sb, fid64->ino, fid64->gen);
 182                 break;
 183         }
 184
 185         return d_obtain_alias(inode);
 186 }
 187
 188 STATIC struct dentry *
 189 xfs_fs_fh_to_parent(struct super_block *sb, struct fid *fid,
 190                  int fh_len, int fileid_type)
 191 {
 192         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
 193         struct inode            *inode = NULL;
 194
 195         if (fh_len < xfs_fileid_length(fileid_type))
 196                 return NULL;
 197
 198         switch (fileid_type) {
 199         case FILEID_INO32_GEN_PARENT:
 200                 inode = xfs_nfs_get_inode(sb, fid->i32.parent_ino,
 201                                               fid->i32.parent_gen);
 202                 break;
 203         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 204                 inode = xfs_nfs_get_inode(sb, fid64->parent_ino,
 205                                               fid64->parent_gen);
 206                 break;
 207         }
 208
 209         return d_obtain_alias(inode);
 210 }
 211
 212 STATIC struct dentry *
 213 xfs_fs_get_parent(
 214         struct dentry           *child)
 215 {
 216         int                     error;
 217         struct xfs_inode        *cip;
 218
 219         error = xfs_lookup(XFS_I(child->d_inode), &xfs_name_dotdot, &cip, NULL);
 220         if (unlikely(error))
 221                 return ERR_PTR(-error);
 222
 223         return d_obtain_alias(VFS_I(cip));
 224 }
 225
 226 STATIC int
 227 xfs_fs_nfs_commit_metadata(
 228         struct inode            *inode)
 229 {
 230         struct xfs_inode        *ip = XFS_I(inode);
 231         struct xfs_mount        *mp = ip->i_mount;
 232         xfs_lsn_t               lsn = 0;
 233
 234         xfs_ilock(ip, XFS_ILOCK_SHARED);
 235         if (xfs_ipincount(ip))
 236                 lsn = ip->i_itemp->ili_last_lsn;
 237         xfs_iunlock(ip, XFS_ILOCK_SHARED);
 238
 239         if (!lsn)
 240                 return 0;
 241         return _xfs_log_force_lsn(mp, lsn, XFS_LOG_SYNC, NULL);
 242 }
 243
 244 const struct export_operations xfs_export_operations = {
 245         .encode_fh              = xfs_fs_encode_fh,
 246         .fh_to_dentry           = xfs_fs_fh_to_dentry,
 247         .fh_to_parent           = xfs_fs_fh_to_parent,
 248         .get_parent             = xfs_fs_get_parent,
 249         .commit_metadata        = xfs_fs_nfs_commit_metadata,
 250 };