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
  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 inode    *inode,
  56         __u32           *fh,
  57         int             *max_len,
  58         struct inode    *parent)
  59 {
  60         struct fid              *fid = (struct fid *)fh;
  61         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fh;
  62         int                     fileid_type;
  63         int                     len;
  64
  65         /* Directories don't need their parent encoded, they have ".." */
  66         if (!parent)
  67                 fileid_type = FILEID_INO32_GEN;
  68         else
  69                 fileid_type = FILEID_INO32_GEN_PARENT;
  70
  71         /*
  72          * If the the filesystem may contain 64bit inode numbers, we need
  73          * to use larger file handles that can represent them.
  74          *
  75          * While we only allocate inodes that do not fit into 32 bits any
  76          * large enough filesystem may contain them, thus the slightly
  77          * confusing looking conditional below.
  78          */
  79         if (!(XFS_M(inode->i_sb)->m_flags & XFS_MOUNT_SMALL_INUMS) ||
  80             (XFS_M(inode->i_sb)->m_flags & XFS_MOUNT_32BITINODES))
  81                 fileid_type |= XFS_FILEID_TYPE_64FLAG;
  82
  83         /*
  84          * Only encode if there is enough space given.  In practice
  85          * this means we can't export a filesystem with 64bit inodes
  86          * over NFSv2 with the subtree_check export option; the other
  87          * seven combinations work.  The real answer is "don't use v2".
  88          */
  89         len = xfs_fileid_length(fileid_type);
  90         if (*max_len < len) {
  91                 *max_len = len;
  92                 return 255;
  93         }
  94         *max_len = len;
  95
  96         switch (fileid_type) {
  97         case FILEID_INO32_GEN_PARENT:
  98                 fid->i32.parent_ino = XFS_I(parent)->i_ino;
  99                 fid->i32.parent_gen = parent->i_generation;
 100                 /*FALLTHRU*/
 101         case FILEID_INO32_GEN:
 102                 fid->i32.ino = XFS_I(inode)->i_ino;
 103                 fid->i32.gen = inode->i_generation;
 104                 break;
 105         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 106                 fid64->parent_ino = XFS_I(parent)->i_ino;
 107                 fid64->parent_gen = parent->i_generation;
 108                 /*FALLTHRU*/
 109         case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
 110                 fid64->ino = XFS_I(inode)->i_ino;
 111                 fid64->gen = inode->i_generation;
 112                 break;
 113         }
 114
 115         return fileid_type;
 116 }
 117
 118 STATIC struct inode *
 119 xfs_nfs_get_inode(
 120         struct super_block      *sb,
 121         u64                     ino,
 122         u32                     generation)
 123  {
 124         xfs_mount_t             *mp = XFS_M(sb);
 125         xfs_inode_t             *ip;
 126         int                     error;
 127
 128         /*
 129          * NFS can sometimes send requests for ino 0.  Fail them gracefully.
 130          */
 131         if (ino == 0)
 132                 return ERR_PTR(-ESTALE);
 133
 134         /*
 135          * The XFS_IGET_UNTRUSTED means that an invalid inode number is just
 136          * fine and not an indication of a corrupted filesystem as clients can
 137          * send invalid file handles and we have to handle it gracefully..
 138          */
 139         error = xfs_iget(mp, NULL, ino, XFS_IGET_UNTRUSTED, 0, &ip);
 140         if (error) {
 141                 /*
 142                  * EINVAL means the inode cluster doesn't exist anymore.
 143                  * This implies the filehandle is stale, so we should
 144                  * translate it here.
 145                  * We don't use ESTALE directly down the chain to not
 146                  * confuse applications using bulkstat that expect EINVAL.
 147                  */
 148                 if (error == EINVAL || error == ENOENT)
 149                         error = ESTALE;
 150                 return ERR_PTR(-error);
 151         }
 152
 153         if (ip->i_d.di_gen != generation) {
 154                 IRELE(ip);
 155                 return ERR_PTR(-ESTALE);
 156         }
 157
 158         return VFS_I(ip);
 159 }
 160
 161 STATIC struct dentry *
 162 xfs_fs_fh_to_dentry(struct super_block *sb, struct fid *fid,
 163                  int fh_len, int fileid_type)
 164 {
 165         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
 166         struct inode            *inode = NULL;
 167
 168         if (fh_len < xfs_fileid_length(fileid_type))
 169                 return NULL;
 170
 171         switch (fileid_type) {
 172         case FILEID_INO32_GEN_PARENT:
 173         case FILEID_INO32_GEN:
 174                 inode = xfs_nfs_get_inode(sb, fid->i32.ino, fid->i32.gen);
 175                 break;
 176         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 177         case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
 178                 inode = xfs_nfs_get_inode(sb, fid64->ino, fid64->gen);
 179                 break;
 180         }
 181
 182         return d_obtain_alias(inode);
 183 }
 184
 185 STATIC struct dentry *
 186 xfs_fs_fh_to_parent(struct super_block *sb, struct fid *fid,
 187                  int fh_len, int fileid_type)
 188 {
 189         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
 190         struct inode            *inode = NULL;
 191
 192         switch (fileid_type) {
 193         case FILEID_INO32_GEN_PARENT:
 194                 inode = xfs_nfs_get_inode(sb, fid->i32.parent_ino,
 195                                               fid->i32.parent_gen);
 196                 break;
 197         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 198                 inode = xfs_nfs_get_inode(sb, fid64->parent_ino,
 199                                               fid64->parent_gen);
 200                 break;
 201         }
 202
 203         return d_obtain_alias(inode);
 204 }
 205
 206 STATIC struct dentry *
 207 xfs_fs_get_parent(
 208         struct dentry           *child)
 209 {
 210         int                     error;
 211         struct xfs_inode        *cip;
 212
 213         error = xfs_lookup(XFS_I(child->d_inode), &xfs_name_dotdot, &cip, NULL);
 214         if (unlikely(error))
 215                 return ERR_PTR(-error);
 216
 217         return d_obtain_alias(VFS_I(cip));
 218 }
 219
 220 STATIC int
 221 xfs_fs_nfs_commit_metadata(
 222         struct inode            *inode)
 223 {
 224         struct xfs_inode        *ip = XFS_I(inode);
 225         struct xfs_mount        *mp = ip->i_mount;
 226         xfs_lsn_t               lsn = 0;
 227
 228         xfs_ilock(ip, XFS_ILOCK_SHARED);
 229         if (xfs_ipincount(ip))
 230                 lsn = ip->i_itemp->ili_last_lsn;
 231         xfs_iunlock(ip, XFS_ILOCK_SHARED);
 232
 233         if (!lsn)
 234                 return 0;
 235         return _xfs_log_force_lsn(mp, lsn, XFS_LOG_SYNC, NULL);
 236 }
 237
 238 const struct export_operations xfs_export_operations = {
 239         .encode_fh              = xfs_fs_encode_fh,
 240         .fh_to_dentry           = xfs_fs_fh_to_dentry,
 241         .fh_to_parent           = xfs_fs_fh_to_parent,
 242         .get_parent             = xfs_fs_get_parent,
 243         .commit_metadata        = xfs_fs_nfs_commit_metadata,
 244 };