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_inum.h"
  21 #include "xfs_log.h"
  22 #include "xfs_trans.h"
  23 #include "xfs_sb.h"
  24 #include "xfs_ag.h"
  25 #include "xfs_dir2.h"
  26 #include "xfs_mount.h"
  27 #include "xfs_export.h"
  28 #include "xfs_vnodeops.h"
  29 #include "xfs_bmap_btree.h"
  30 #include "xfs_inode.h"
  31 #include "xfs_inode_item.h"
  32 #include "xfs_trace.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 255; /* invalid */
  52 }
  53
  54 STATIC int
  55 xfs_fs_encode_fh(
  56         struct dentry           *dentry,
  57         __u32                   *fh,
  58         int                     *max_len,
  59         int                     connectable)
  60 {
  61         struct fid              *fid = (struct fid *)fh;
  62         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fh;
  63         struct inode            *inode = dentry->d_inode;
  64         int                     fileid_type;
  65         int                     len;
  66
  67         /* Directories don't need their parent encoded, they have ".." */
  68         if (S_ISDIR(inode->i_mode) || !connectable)
  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 255;
  95         }
  96         *max_len = len;
  97
  98         switch (fileid_type) {
  99         case FILEID_INO32_GEN_PARENT:
 100                 spin_lock(&dentry->d_lock);
 101                 fid->i32.parent_ino = dentry->d_parent->d_inode->i_ino;
 102                 fid->i32.parent_gen = dentry->d_parent->d_inode->i_generation;
 103                 spin_unlock(&dentry->d_lock);
 104                 /*FALLTHRU*/
 105         case FILEID_INO32_GEN:
 106                 fid->i32.ino = inode->i_ino;
 107                 fid->i32.gen = inode->i_generation;
 108                 break;
 109         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 110                 spin_lock(&dentry->d_lock);
 111                 fid64->parent_ino = dentry->d_parent->d_inode->i_ino;
 112                 fid64->parent_gen = dentry->d_parent->d_inode->i_generation;
 113                 spin_unlock(&dentry->d_lock);
 114                 /*FALLTHRU*/
 115         case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
 116                 fid64->ino = inode->i_ino;
 117                 fid64->gen = inode->i_generation;
 118                 break;
 119         }
 120
 121         return fileid_type;
 122 }
 123
 124 STATIC struct inode *
 125 xfs_nfs_get_inode(
 126         struct super_block      *sb,
 127         u64                     ino,
 128         u32                     generation)
 129  {
 130         xfs_mount_t             *mp = XFS_M(sb);
 131         xfs_inode_t             *ip;
 132         int                     error;
 133
 134         /*
 135          * NFS can sometimes send requests for ino 0.  Fail them gracefully.
 136          */
 137         if (ino == 0)
 138                 return ERR_PTR(-ESTALE);
 139
 140         /*
 141          * The XFS_IGET_UNTRUSTED means that an invalid inode number is just
 142          * fine and not an indication of a corrupted filesystem as clients can
 143          * send invalid file handles and we have to handle it gracefully..
 144          */
 145         error = xfs_iget(mp, NULL, ino, XFS_IGET_UNTRUSTED, 0, &ip);
 146         if (error) {
 147                 /*
 148                  * EINVAL means the inode cluster doesn't exist anymore.
 149                  * This implies the filehandle is stale, so we should
 150                  * translate it here.
 151                  * We don't use ESTALE directly down the chain to not
 152                  * confuse applications using bulkstat that expect EINVAL.
 153                  */
 154                 if (error == EINVAL || error == ENOENT)
 155                         error = ESTALE;
 156                 return ERR_PTR(-error);
 157         }
 158
 159         if (ip->i_d.di_gen != generation) {
 160                 IRELE(ip);
 161                 return ERR_PTR(-ESTALE);
 162         }
 163
 164         return VFS_I(ip);
 165 }
 166
 167 STATIC struct dentry *
 168 xfs_fs_fh_to_dentry(struct super_block *sb, struct fid *fid,
 169                  int fh_len, int fileid_type)
 170 {
 171         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
 172         struct inode            *inode = NULL;
 173
 174         if (fh_len < xfs_fileid_length(fileid_type))
 175                 return NULL;
 176
 177         switch (fileid_type) {
 178         case FILEID_INO32_GEN_PARENT:
 179         case FILEID_INO32_GEN:
 180                 inode = xfs_nfs_get_inode(sb, fid->i32.ino, fid->i32.gen);
 181                 break;
 182         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 183         case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
 184                 inode = xfs_nfs_get_inode(sb, fid64->ino, fid64->gen);
 185                 break;
 186         }
 187
 188         return d_obtain_alias(inode);
 189 }
 190
 191 STATIC struct dentry *
 192 xfs_fs_fh_to_parent(struct super_block *sb, struct fid *fid,
 193                  int fh_len, int fileid_type)
 194 {
 195         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
 196         struct inode            *inode = 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         int                     error = 0;
 233
 234         xfs_ilock(ip, XFS_ILOCK_SHARED);
 235         if (xfs_ipincount(ip)) {
 236                 error = _xfs_log_force_lsn(mp, ip->i_itemp->ili_last_lsn,
 237                                 XFS_LOG_SYNC, NULL);
 238         }
 239         xfs_iunlock(ip, XFS_ILOCK_SHARED);
 240
 241         return error;
 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 };