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_format.h"
   8 #include "xfs_log_format.h"
   9 #include "xfs_trans_resv.h"
  10 #include "xfs_mount.h"
  11 #include "xfs_da_format.h"
  12 #include "xfs_da_btree.h"
  13 #include "xfs_dir2.h"
  14 #include "xfs_export.h"
  15 #include "xfs_inode.h"
  16 #include "xfs_trans.h"
  17 #include "xfs_inode_item.h"
  18 #include "xfs_trace.h"
  19 #include "xfs_icache.h"
  20 #include "xfs_log.h"
  21 #include "xfs_pnfs.h"
  22
  23 /*
  24  * Note that we only accept fileids which are long enough rather than allow
  25  * the parent generation number to default to zero.  XFS considers zero a
  26  * valid generation number not an invalid/wildcard value.
  27  */
  28 static int xfs_fileid_length(int fileid_type)
  29 {
  30         switch (fileid_type) {
  31         case FILEID_INO32_GEN:
  32                 return 2;
  33         case FILEID_INO32_GEN_PARENT:
  34                 return 4;
  35         case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
  36                 return 3;
  37         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
  38                 return 6;
  39         }
  40         return FILEID_INVALID;
  41 }
  42
  43 STATIC int
  44 xfs_fs_encode_fh(
  45         struct inode    *inode,
  46         __u32           *fh,
  47         int             *max_len,
  48         struct inode    *parent)
  49 {
  50         struct fid              *fid = (struct fid *)fh;
  51         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fh;
  52         int                     fileid_type;
  53         int                     len;
  54
  55         /* Directories don't need their parent encoded, they have ".." */
  56         if (!parent)
  57                 fileid_type = FILEID_INO32_GEN;
  58         else
  59                 fileid_type = FILEID_INO32_GEN_PARENT;
  60
  61         /*
  62          * If the the filesystem may contain 64bit inode numbers, we need
  63          * to use larger file handles that can represent them.
  64          *
  65          * While we only allocate inodes that do not fit into 32 bits any
  66          * large enough filesystem may contain them, thus the slightly
  67          * confusing looking conditional below.
  68          */
  69         if (!(XFS_M(inode->i_sb)->m_flags & XFS_MOUNT_SMALL_INUMS) ||
  70             (XFS_M(inode->i_sb)->m_flags & XFS_MOUNT_32BITINODES))
  71                 fileid_type |= XFS_FILEID_TYPE_64FLAG;
  72
  73         /*
  74          * Only encode if there is enough space given.  In practice
  75          * this means we can't export a filesystem with 64bit inodes
  76          * over NFSv2 with the subtree_check export option; the other
  77          * seven combinations work.  The real answer is "don't use v2".
  78          */
  79         len = xfs_fileid_length(fileid_type);
  80         if (*max_len < len) {
  81                 *max_len = len;
  82                 return FILEID_INVALID;
  83         }
  84         *max_len = len;
  85
  86         switch (fileid_type) {
  87         case FILEID_INO32_GEN_PARENT:
  88                 fid->i32.parent_ino = XFS_I(parent)->i_ino;
  89                 fid->i32.parent_gen = parent->i_generation;
  90                 /*FALLTHRU*/
  91         case FILEID_INO32_GEN:
  92                 fid->i32.ino = XFS_I(inode)->i_ino;
  93                 fid->i32.gen = inode->i_generation;
  94                 break;
  95         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
  96                 fid64->parent_ino = XFS_I(parent)->i_ino;
  97                 fid64->parent_gen = parent->i_generation;
  98                 /*FALLTHRU*/
  99         case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
 100                 fid64->ino = XFS_I(inode)->i_ino;
 101                 fid64->gen = inode->i_generation;
 102                 break;
 103         }
 104
 105         return fileid_type;
 106 }
 107
 108 STATIC struct inode *
 109 xfs_nfs_get_inode(
 110         struct super_block      *sb,
 111         u64                     ino,
 112         u32                     generation)
 113 {
 114         xfs_mount_t             *mp = XFS_M(sb);
 115         xfs_inode_t             *ip;
 116         int                     error;
 117
 118         /*
 119          * NFS can sometimes send requests for ino 0.  Fail them gracefully.
 120          */
 121         if (ino == 0)
 122                 return ERR_PTR(-ESTALE);
 123
 124         /*
 125          * The XFS_IGET_UNTRUSTED means that an invalid inode number is just
 126          * fine and not an indication of a corrupted filesystem as clients can
 127          * send invalid file handles and we have to handle it gracefully..
 128          */
 129         error = xfs_iget(mp, NULL, ino, XFS_IGET_UNTRUSTED, 0, &ip);
 130         if (error) {
 131
 132                 /*
 133                  * EINVAL means the inode cluster doesn't exist anymore.
 134                  * EFSCORRUPTED means the metadata pointing to the inode cluster
 135                  * or the inode cluster itself is corrupt.  This implies the
 136                  * filehandle is stale, so we should translate it here.
 137                  * We don't use ESTALE directly down the chain to not
 138                  * confuse applications using bulkstat that expect EINVAL.
 139                  */
 140                 switch (error) {
 141                 case -EINVAL:
 142                 case -ENOENT:
 143                 case -EFSCORRUPTED:
 144                         error = -ESTALE;
 145                         break;
 146                 default:
 147                         break;
 148                 }
 149                 return ERR_PTR(error);
 150         }
 151
 152         if (VFS_I(ip)->i_generation != generation) {
 153                 xfs_irele(ip);
 154                 return ERR_PTR(-ESTALE);
 155         }
 156
 157         return VFS_I(ip);
 158 }
 159
 160 STATIC struct dentry *
 161 xfs_fs_fh_to_dentry(struct super_block *sb, struct fid *fid,
 162                  int fh_len, int fileid_type)
 163 {
 164         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
 165         struct inode            *inode = NULL;
 166
 167         if (fh_len < xfs_fileid_length(fileid_type))
 168                 return NULL;
 169
 170         switch (fileid_type) {
 171         case FILEID_INO32_GEN_PARENT:
 172         case FILEID_INO32_GEN:
 173                 inode = xfs_nfs_get_inode(sb, fid->i32.ino, fid->i32.gen);
 174                 break;
 175         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 176         case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
 177                 inode = xfs_nfs_get_inode(sb, fid64->ino, fid64->gen);
 178                 break;
 179         }
 180
 181         return d_obtain_alias(inode);
 182 }
 183
 184 STATIC struct dentry *
 185 xfs_fs_fh_to_parent(struct super_block *sb, struct fid *fid,
 186                  int fh_len, int fileid_type)
 187 {
 188         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
 189         struct inode            *inode = NULL;
 190
 191         if (fh_len < xfs_fileid_length(fileid_type))
 192                 return NULL;
 193
 194         switch (fileid_type) {
 195         case FILEID_INO32_GEN_PARENT:
 196                 inode = xfs_nfs_get_inode(sb, fid->i32.parent_ino,
 197                                               fid->i32.parent_gen);
 198                 break;
 199         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 200                 inode = xfs_nfs_get_inode(sb, fid64->parent_ino,
 201                                               fid64->parent_gen);
 202                 break;
 203         }
 204
 205         return d_obtain_alias(inode);
 206 }
 207
 208 STATIC struct dentry *
 209 xfs_fs_get_parent(
 210         struct dentry           *child)
 211 {
 212         int                     error;
 213         struct xfs_inode        *cip;
 214
 215         error = xfs_lookup(XFS_I(d_inode(child)), &xfs_name_dotdot, &cip, NULL);
 216         if (unlikely(error))
 217                 return ERR_PTR(error);
 218
 219         return d_obtain_alias(VFS_I(cip));
 220 }
 221
 222 STATIC int
 223 xfs_fs_nfs_commit_metadata(
 224         struct inode            *inode)
 225 {
 226         struct xfs_inode        *ip = XFS_I(inode);
 227         struct xfs_mount        *mp = ip->i_mount;
 228         xfs_lsn_t               lsn = 0;
 229
 230         xfs_ilock(ip, XFS_ILOCK_SHARED);
 231         if (xfs_ipincount(ip))
 232                 lsn = ip->i_itemp->ili_last_lsn;
 233         xfs_iunlock(ip, XFS_ILOCK_SHARED);
 234
 235         if (!lsn)
 236                 return 0;
 237         return xfs_log_force_lsn(mp, lsn, XFS_LOG_SYNC, NULL);
 238 }
 239
 240 const struct export_operations xfs_export_operations = {
 241         .encode_fh              = xfs_fs_encode_fh,
 242         .fh_to_dentry           = xfs_fs_fh_to_dentry,
 243         .fh_to_parent           = xfs_fs_fh_to_parent,
 244         .get_parent             = xfs_fs_get_parent,
 245         .commit_metadata        = xfs_fs_nfs_commit_metadata,
 246 #ifdef CONFIG_EXPORTFS_BLOCK_OPS
 247         .get_uuid               = xfs_fs_get_uuid,
 248         .map_blocks             = xfs_fs_map_blocks,
 249         .commit_blocks          = xfs_fs_commit_blocks,
 250 #endif
 251 };