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 dentry           *dentry,
  56         __u32                   *fh,
  57         int                     *max_len,
  58         int                     connectable)
  59 {
  60         struct fid              *fid = (struct fid *)fh;
  61         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fh;
  62         struct inode            *inode = dentry->d_inode;
  63         int                     fileid_type;
  64         int                     len;
  65
  66         /* Directories don't need their parent encoded, they have ".." */
  67         if (S_ISDIR(inode->i_mode) || !connectable)
  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 255;
  94         }
  95         *max_len = len;
  96
  97         switch (fileid_type) {
  98         case FILEID_INO32_GEN_PARENT:
  99                 spin_lock(&dentry->d_lock);
 100                 fid->i32.parent_ino = XFS_I(dentry->d_parent->d_inode)->i_ino;
 101                 fid->i32.parent_gen = dentry->d_parent->d_inode->i_generation;
 102                 spin_unlock(&dentry->d_lock);
 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                 spin_lock(&dentry->d_lock);
 110                 fid64->parent_ino = XFS_I(dentry->d_parent->d_inode)->i_ino;
 111                 fid64->parent_gen = dentry->d_parent->d_inode->i_generation;
 112                 spin_unlock(&dentry->d_lock);
 113                 /*FALLTHRU*/
 114         case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
 115                 fid64->ino = XFS_I(inode)->i_ino;
 116                 fid64->gen = inode->i_generation;
 117                 break;
 118         }
 119
 120         return fileid_type;
 121 }
 122
 123 STATIC struct inode *
 124 xfs_nfs_get_inode(
 125         struct super_block      *sb,
 126         u64                     ino,
 127         u32                     generation)
 128  {
 129         xfs_mount_t             *mp = XFS_M(sb);
 130         xfs_inode_t             *ip;
 131         int                     error;
 132
 133         /*
 134          * NFS can sometimes send requests for ino 0.  Fail them gracefully.
 135          */
 136         if (ino == 0)
 137                 return ERR_PTR(-ESTALE);
 138
 139         /*
 140          * The XFS_IGET_UNTRUSTED means that an invalid inode number is just
 141          * fine and not an indication of a corrupted filesystem as clients can
 142          * send invalid file handles and we have to handle it gracefully..
 143          */
 144         error = xfs_iget(mp, NULL, ino, XFS_IGET_UNTRUSTED, 0, &ip);
 145         if (error) {
 146                 /*
 147                  * EINVAL means the inode cluster doesn't exist anymore.
 148                  * This implies the filehandle is stale, so we should
 149                  * translate it here.
 150                  * We don't use ESTALE directly down the chain to not
 151                  * confuse applications using bulkstat that expect EINVAL.
 152                  */
 153                 if (error == EINVAL || error == ENOENT)
 154                         error = ESTALE;
 155                 return ERR_PTR(-error);
 156         }
 157
 158         if (ip->i_d.di_gen != generation) {
 159                 IRELE(ip);
 160                 return ERR_PTR(-ESTALE);
 161         }
 162
 163         return VFS_I(ip);
 164 }
 165
 166 STATIC struct dentry *
 167 xfs_fs_fh_to_dentry(struct super_block *sb, struct fid *fid,
 168                  int fh_len, int fileid_type)
 169 {
 170         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
 171         struct inode            *inode = NULL;
 172
 173         if (fh_len < xfs_fileid_length(fileid_type))
 174                 return NULL;
 175
 176         switch (fileid_type) {
 177         case FILEID_INO32_GEN_PARENT:
 178         case FILEID_INO32_GEN:
 179                 inode = xfs_nfs_get_inode(sb, fid->i32.ino, fid->i32.gen);
 180                 break;
 181         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 182         case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
 183                 inode = xfs_nfs_get_inode(sb, fid64->ino, fid64->gen);
 184                 break;
 185         }
 186
 187         return d_obtain_alias(inode);
 188 }
 189
 190 STATIC struct dentry *
 191 xfs_fs_fh_to_parent(struct super_block *sb, struct fid *fid,
 192                  int fh_len, int fileid_type)
 193 {
 194         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
 195         struct inode            *inode = 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 };