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_log.h"
  19 #include "xfs_pnfs.h"
  20
  21 /*
  22  * Note that we only accept fileids which are long enough rather than allow
  23  * the parent generation number to default to zero.  XFS considers zero a
  24  * valid generation number not an invalid/wildcard value.
  25  */
  26 static int xfs_fileid_length(int fileid_type)
  27 {
  28         switch (fileid_type) {
  29         case FILEID_INO32_GEN:
  30                 return 2;
  31         case FILEID_INO32_GEN_PARENT:
  32                 return 4;
  33         case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
  34                 return 3;
  35         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
  36                 return 6;
  37         }
  38         return FILEID_INVALID;
  39 }
  40
  41 STATIC int
  42 xfs_fs_encode_fh(
  43         struct inode    *inode,
  44         __u32           *fh,
  45         int             *max_len,
  46         struct inode    *parent)
  47 {
  48         struct fid              *fid = (struct fid *)fh;
  49         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fh;
  50         int                     fileid_type;
  51         int                     len;
  52
  53         /* Directories don't need their parent encoded, they have ".." */
  54         if (!parent)
  55                 fileid_type = FILEID_INO32_GEN;
  56         else
  57                 fileid_type = FILEID_INO32_GEN_PARENT;
  58
  59         /*
  60          * If the the filesystem may contain 64bit inode numbers, we need
  61          * to use larger file handles that can represent them.
  62          *
  63          * While we only allocate inodes that do not fit into 32 bits any
  64          * large enough filesystem may contain them, thus the slightly
  65          * confusing looking conditional below.
  66          */
  67         if (!(XFS_M(inode->i_sb)->m_flags & XFS_MOUNT_SMALL_INUMS) ||
  68             (XFS_M(inode->i_sb)->m_flags & XFS_MOUNT_32BITINODES))
  69                 fileid_type |= XFS_FILEID_TYPE_64FLAG;
  70
  71         /*
  72          * Only encode if there is enough space given.  In practice
  73          * this means we can't export a filesystem with 64bit inodes
  74          * over NFSv2 with the subtree_check export option; the other
  75          * seven combinations work.  The real answer is "don't use v2".
  76          */
  77         len = xfs_fileid_length(fileid_type);
  78         if (*max_len < len) {
  79                 *max_len = len;
  80                 return FILEID_INVALID;
  81         }
  82         *max_len = len;
  83
  84         switch (fileid_type) {
  85         case FILEID_INO32_GEN_PARENT:
  86                 fid->i32.parent_ino = XFS_I(parent)->i_ino;
  87                 fid->i32.parent_gen = parent->i_generation;
  88                 /*FALLTHRU*/
  89         case FILEID_INO32_GEN:
  90                 fid->i32.ino = XFS_I(inode)->i_ino;
  91                 fid->i32.gen = inode->i_generation;
  92                 break;
  93         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
  94                 fid64->parent_ino = XFS_I(parent)->i_ino;
  95                 fid64->parent_gen = parent->i_generation;
  96                 /*FALLTHRU*/
  97         case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
  98                 fid64->ino = XFS_I(inode)->i_ino;
  99                 fid64->gen = inode->i_generation;
 100                 break;
 101         }
 102
 103         return fileid_type;
 104 }
 105
 106 STATIC struct inode *
 107 xfs_nfs_get_inode(
 108         struct super_block      *sb,
 109         u64                     ino,
 110         u32                     generation)
 111 {
 112         xfs_mount_t             *mp = XFS_M(sb);
 113         xfs_inode_t             *ip;
 114         int                     error;
 115
 116         /*
 117          * NFS can sometimes send requests for ino 0.  Fail them gracefully.
 118          */
 119         if (ino == 0)
 120                 return ERR_PTR(-ESTALE);
 121
 122         /*
 123          * The XFS_IGET_UNTRUSTED means that an invalid inode number is just
 124          * fine and not an indication of a corrupted filesystem as clients can
 125          * send invalid file handles and we have to handle it gracefully..
 126          */
 127         error = xfs_iget(mp, NULL, ino, XFS_IGET_UNTRUSTED, 0, &ip);
 128         if (error) {
 129
 130                 /*
 131                  * EINVAL means the inode cluster doesn't exist anymore.
 132                  * EFSCORRUPTED means the metadata pointing to the inode cluster
 133                  * or the inode cluster itself is corrupt.  This implies the
 134                  * filehandle is stale, so we should translate it here.
 135                  * We don't use ESTALE directly down the chain to not
 136                  * confuse applications using bulkstat that expect EINVAL.
 137                  */
 138                 switch (error) {
 139                 case -EINVAL:
 140                 case -ENOENT:
 141                 case -EFSCORRUPTED:
 142                         error = -ESTALE;
 143                         break;
 144                 default:
 145                         break;
 146                 }
 147                 return ERR_PTR(error);
 148         }
 149
 150         if (VFS_I(ip)->i_generation != generation) {
 151                 xfs_irele(ip);
 152                 return ERR_PTR(-ESTALE);
 153         }
 154
 155         return VFS_I(ip);
 156 }
 157
 158 STATIC struct dentry *
 159 xfs_fs_fh_to_dentry(struct super_block *sb, struct fid *fid,
 160                  int fh_len, int fileid_type)
 161 {
 162         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
 163         struct inode            *inode = NULL;
 164
 165         if (fh_len < xfs_fileid_length(fileid_type))
 166                 return NULL;
 167
 168         switch (fileid_type) {
 169         case FILEID_INO32_GEN_PARENT:
 170         case FILEID_INO32_GEN:
 171                 inode = xfs_nfs_get_inode(sb, fid->i32.ino, fid->i32.gen);
 172                 break;
 173         case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 174         case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
 175                 inode = xfs_nfs_get_inode(sb, fid64->ino, fid64->gen);
 176                 break;
 177         }
 178
 179         return d_obtain_alias(inode);
 180 }
 181
 182 STATIC struct dentry *
 183 xfs_fs_fh_to_parent(struct super_block *sb, struct fid *fid,
 184                  int fh_len, int fileid_type)
 185 {
 186         struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
 187         struct inode            *inode = NULL;
 188
 189         if (fh_len < xfs_fileid_length(fileid_type))
 190                 return 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(d_inode(child)), &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 #ifdef CONFIG_EXPORTFS_BLOCK_OPS
 245         .get_uuid               = xfs_fs_get_uuid,
 246         .map_blocks             = xfs_fs_map_blocks,
 247         .commit_blocks          = xfs_fs_commit_blocks,
 248 #endif
 249 };