kill-i_version-support-for-hurd-OS-filesystems

   1 ext4: kill i_version support for Hurd-castrated file systems
   2
   3 The Hurd file system uses uses the inode field which is now used for
   4 i_version for its translator block.  This means that ext2 file systems
   5 that are formatted for GNU Hurd can't be used to support NFSv4.  Given
   6 that Hurd file systems don't support extents, and a huge number of
   7 modern file system features, this is no great loss.
   8
   9 If we don't do this, the attempt to update the i_version field will
  10 stomp over the translator block field, which will cause file system
  11 corruption for Hurd file systems.  This can be replicated via:
  12
  13 mke2fs -t ext2 -o hurd /dev/vdc
  14 mount -t ext4 /dev/vdc /vdc
  15 touch /vdc/bug0000
  16 umount /dev/vdc
  17 e2fsck -f /dev/vdc
  18
  19 Addresses-Debian-Bug: #738758
  20
  21 Reported-By: Gabriele Giacone <1o5g4r8o@gmail.com>
  22 Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
  23 ---
  24  fs/ext4/inode.c | 29 ++++++++++++++++++-----------
  25  1 file changed, 18 insertions(+), 11 deletions(-)
  26
  27 diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
  28 index 7cc2455..ed2c13a 100644
  29 --- a/fs/ext4/inode.c
  30 +++ b/fs/ext4/inode.c
  31 @@ -4168,11 +4168,14 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
  32         EXT4_INODE_GET_XTIME(i_atime, inode, raw_inode);
  33         EXT4_EINODE_GET_XTIME(i_crtime, ei, raw_inode);
  34
  35 -       inode->i_version = le32_to_cpu(raw_inode->i_disk_version);
  36 -       if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
  37 -               if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi))
  38 -                       inode->i_version |=
  39 -                       (__u64)(le32_to_cpu(raw_inode->i_version_hi)) << 32;
  40 +       if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
  41 +           cpu_to_le32(EXT4_OS_HURD)) {
  42 +               inode->i_version = le32_to_cpu(raw_inode->i_disk_version);
  43 +               if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
  44 +                       if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi))
  45 +                               inode->i_version |=
  46 +                   (__u64)(le32_to_cpu(raw_inode->i_version_hi)) << 32;
  47 +               }
  48         }
  49
  50         ret = 0;
  51 @@ -4388,12 +4391,16 @@ static int ext4_do_update_inode(handle_t *handle,
  52                         raw_inode->i_block[block] = ei->i_data[block];
  53         }
  54
  55 -       raw_inode->i_disk_version = cpu_to_le32(inode->i_version);
  56 -       if (ei->i_extra_isize) {
  57 -               if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi))
  58 -                       raw_inode->i_version_hi =
  59 -                       cpu_to_le32(inode->i_version >> 32);
  60 -               raw_inode->i_extra_isize = cpu_to_le16(ei->i_extra_isize);
  61 +       if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
  62 +           cpu_to_le32(EXT4_OS_HURD)) {
  63 +               raw_inode->i_disk_version = cpu_to_le32(inode->i_version);
  64 +               if (ei->i_extra_isize) {
  65 +                       if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi))
  66 +                               raw_inode->i_version_hi =
  67 +                                       cpu_to_le32(inode->i_version >> 32);
  68 +                       raw_inode->i_extra_isize =
  69 +                               cpu_to_le16(ei->i_extra_isize);
  70 +               }
  71         }
  72
  73         ext4_inode_csum_set(inode, raw_inode, ei);