fs/xfs/xfs_export.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (c) 2004-2005 Silicon Graphics, Inc.
   4  * All Rights Reserved.
   5  */
   6 #include "xfs.h"
   7 #include "xfs_shared.h"
   8 #include "xfs_format.h"
   9 #include "xfs_log_format.h"
  10 #include "xfs_trans_resv.h"
  11 #include "xfs_mount.h"
  12 #include "xfs_dir2.h"
  13 #include "xfs_export.h"
  14 #include "xfs_inode.h"
  15 #include "xfs_trans.h"
  16 #include "xfs_inode_item.h"
  17 #include "xfs_icache.h"
  18 #include "xfs_pnfs.h"
  19
  20 /*
  21  * Note that we only accept fileids which are long enough rather than allow
  22  * the parent generation number to default to zero.  XFS considers zero a
  23  * valid generation number not an invalid/wildcard value.
  24  */
  25 static int xfs_fileid_length(int fileid_type)
  26 {
  27         switch (fileid_type) {
  28         case FILEID_INO32_GEN:
  29                 return 2;
  30         case FILEID_INO32_GEN_PARENT:
  31                 return 4;
  32         case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
  33                 return 3;
  34         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
  35                 return 6;
  36         }
  37         return FILEID_INVALID;
  38 }
  39
  40 STATIC int
  41 xfs_fs_encode_fh(
  42         struct inode    *inode,
  43         __u32           *fh,
  44         int             *max_len,
  45         struct inode    *parent)
  46 {
  47         struct fid              *fid = (struct fid *)fh;
  48         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fh;
  49         int                     fileid_type;
  50         int                     len;
  51
  52         /* Directories don't need their parent encoded, they have ".." */
  53         if (!parent)
  54                 fileid_type = FILEID_INO32_GEN;
  55         else
  56                 fileid_type = FILEID_INO32_GEN_PARENT;
  57
  58         /*
  59          * If the filesystem may contain 64bit inode numbers, we need
  60          * to use larger file handles that can represent them.
  61          *
  62          * While we only allocate inodes that do not fit into 32 bits any
  63          * large enough filesystem may contain them, thus the slightly
  64          * confusing looking conditional below.
  65          */
  66         if (!(XFS_M(inode->i_sb)->m_flags & XFS_MOUNT_SMALL_INUMS) ||
  67             (XFS_M(inode->i_sb)->m_flags & XFS_MOUNT_32BITINODES))
  68                 fileid_type |= XFS_FILEID_TYPE_64FLAG;
  69
  70         /*
  71          * Only encode if there is enough space given.  In practice
  72          * this means we can't export a filesystem with 64bit inodes
  73          * over NFSv2 with the subtree_check export option; the other
  74          * seven combinations work.  The real answer is "don't use v2".
  75          */
  76         len = xfs_fileid_length(fileid_type);
  77         if (*max_len < len) {
  78                 *max_len = len;
  79                 return FILEID_INVALID;
  80         }
  81         *max_len = len;
  82
  83         switch (fileid_type) {
  84         case FILEID_INO32_GEN_PARENT:
  85                 fid->i32.parent_ino = XFS_I(parent)->i_ino;
  86                 fid->i32.parent_gen = parent->i_generation;
  87                 /*FALLTHRU*/
  88         case FILEID_INO32_GEN:
  89                 fid->i32.ino = XFS_I(inode)->i_ino;
  90                 fid->i32.gen = inode->i_generation;
  91                 break;
  92         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
  93                 fid64->parent_ino = XFS_I(parent)->i_ino;
  94                 fid64->parent_gen = parent->i_generation;
  95                 /*FALLTHRU*/
  96         case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
  97                 fid64->ino = XFS_I(inode)->i_ino;
  98                 fid64->gen = inode->i_generation;
  99                 break;
 100         }
 101
 102         return fileid_type;
 103 }
 104
 105 STATIC struct inode *
 106 xfs_nfs_get_inode(
 107         struct super_block      *sb,
 108         u64                     ino,
 109         u32                     generation)
 110 {
 111         xfs_mount_t             *mp = XFS_M(sb);
 112         xfs_inode_t             *ip;
 113         int                     error;
 114
 115         /*
 116          * NFS can sometimes send requests for ino 0.  Fail them gracefully.
 117          */
 118         if (ino == 0)
 119                 return ERR_PTR(-ESTALE);
 120
 121         /*
 122          * The XFS_IGET_UNTRUSTED means that an invalid inode number is just
 123          * fine and not an indication of a corrupted filesystem as clients can
 124          * send invalid file handles and we have to handle it gracefully..
 125          */
 126         error = xfs_iget(mp, NULL, ino, XFS_IGET_UNTRUSTED, 0, &ip);
 127         if (error) {
 128
 129                 /*
 130                  * EINVAL means the inode cluster doesn't exist anymore.
 131                  * EFSCORRUPTED means the metadata pointing to the inode cluster
 132                  * or the inode cluster itself is corrupt.  This implies the
 133                  * filehandle is stale, so we should translate it here.
 134                  * We don't use ESTALE directly down the chain to not
 135                  * confuse applications using bulkstat that expect EINVAL.
 136                  */
 137                 switch (error) {
 138                 case -EINVAL:
 139                 case -ENOENT:
 140                 case -EFSCORRUPTED:
 141                         error = -ESTALE;
 142                         break;
 143                 default:
 144                         break;
 145                 }
 146                 return ERR_PTR(error);
 147         }
 148
 149         if (VFS_I(ip)->i_generation != generation) {
 150                 xfs_irele(ip);
 151                 return ERR_PTR(-ESTALE);
 152         }
 153
 154         return VFS_I(ip);
 155 }
 156
 157 STATIC struct dentry *
 158 xfs_fs_fh_to_dentry(struct super_block *sb, struct fid *fid,
 159                  int fh_len, int fileid_type)
 160 {
 161         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
 162         struct inode            *inode = NULL;
 163
 164         if (fh_len < xfs_fileid_length(fileid_type))
 165                 return NULL;
 166
 167         switch (fileid_type) {
 168         case FILEID_INO32_GEN_PARENT:
 169         case FILEID_INO32_GEN:
 170                 inode = xfs_nfs_get_inode(sb, fid->i32.ino, fid->i32.gen);
 171                 break;
 172         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 173         case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
 174                 inode = xfs_nfs_get_inode(sb, fid64->ino, fid64->gen);
 175                 break;
 176         }
 177
 178         return d_obtain_alias(inode);
 179 }
 180
 181 STATIC struct dentry *
 182 xfs_fs_fh_to_parent(struct super_block *sb, struct fid *fid,
 183                  int fh_len, int fileid_type)
 184 {
 185         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
 186         struct inode            *inode = NULL;
 187
 188         if (fh_len < xfs_fileid_length(fileid_type))
 189                 return NULL;
 190
 191         switch (fileid_type) {
 192         case FILEID_INO32_GEN_PARENT:
 193                 inode = xfs_nfs_get_inode(sb, fid->i32.parent_ino,
 194                                               fid->i32.parent_gen);
 195                 break;
 196         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 197                 inode = xfs_nfs_get_inode(sb, fid64->parent_ino,
 198                                               fid64->parent_gen);
 199                 break;
 200         }
 201
 202         return d_obtain_alias(inode);
 203 }
 204
 205 STATIC struct dentry *
 206 xfs_fs_get_parent(
 207         struct dentry           *child)
 208 {
 209         int                     error;
 210         struct xfs_inode        *cip;
 211
 212         error = xfs_lookup(XFS_I(d_inode(child)), &xfs_name_dotdot, &cip, NULL);
 213         if (unlikely(error))
 214                 return ERR_PTR(error);
 215
 216         return d_obtain_alias(VFS_I(cip));
 217 }
 218
 219 STATIC int
 220 xfs_fs_nfs_commit_metadata(
 221         struct inode            *inode)
 222 {
 223         return xfs_log_force_inode(XFS_I(inode));
 224 }
 225
 226 const struct export_operations xfs_export_operations = {
 227         .encode_fh              = xfs_fs_encode_fh,
 228         .fh_to_dentry           = xfs_fs_fh_to_dentry,
 229         .fh_to_parent           = xfs_fs_fh_to_parent,
 230         .get_parent             = xfs_fs_get_parent,
 231         .commit_metadata        = xfs_fs_nfs_commit_metadata,
 232 #ifdef CONFIG_EXPORTFS_BLOCK_OPS
 233         .get_uuid               = xfs_fs_get_uuid,
 234         .map_blocks             = xfs_fs_map_blocks,
 235         .commit_blocks          = xfs_fs_commit_blocks,
 236 #endif
 237 };