Probably worthwhile to make those !EXT4_OS_HURD checks likely()?
Cheers, Andreas
> On Mar 19, 2014, at 22:34, Theodore Ts'o <tytso@xxxxxxx> wrote:
>
> The Hurd file system uses uses the inode field which is now used for
> i_version for its translator block. This means that ext2 file systems
> that are formatted for GNU Hurd can't be used to support NFSv4. Given
> that Hurd file systems don't support extents, and a huge number of
> modern file system features, this is no great loss.
>
> If we don't do this, the attempt to update the i_version field will
> stomp over the translator block field, which will cause file system
> corruption for Hurd file systems. This can be replicated via:
>
> mke2fs -t ext2 -o hurd /dev/vdc
> mount -t ext4 /dev/vdc /vdc
> touch /vdc/bug0000
> umount /dev/vdc
> e2fsck -f /dev/vdc
>
> Addresses-Debian-Bug: #738758
>
> Reported-By: Gabriele Giacone <1o5g4r8o@xxxxxxxxx>
> Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx>
> ---
> fs/ext4/inode.c | 29 ++++++++++++++++++-----------
> 1 file changed, 18 insertions(+), 11 deletions(-)
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 7cc2455..ed2c13a 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -4168,11 +4168,14 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
> EXT4_INODE_GET_XTIME(i_atime, inode, raw_inode);
> EXT4_EINODE_GET_XTIME(i_crtime, ei, raw_inode);
>
> - inode->i_version = le32_to_cpu(raw_inode->i_disk_version);
> - if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
> - if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi))
> - inode->i_version |=
> - (__u64)(le32_to_cpu(raw_inode->i_version_hi)) << 32;
> + if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
> + cpu_to_le32(EXT4_OS_HURD)) {
> + inode->i_version = le32_to_cpu(raw_inode->i_disk_version);
> + if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
> + if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi))
> + inode->i_version |=
> + (__u64)(le32_to_cpu(raw_inode->i_version_hi)) << 32;
> + }
> }
>
> ret = 0;
> @@ -4388,12 +4391,16 @@ static int ext4_do_update_inode(handle_t *handle,
> raw_inode->i_block[block] = ei->i_data[block];
> }
>
> - raw_inode->i_disk_version = cpu_to_le32(inode->i_version);
> - if (ei->i_extra_isize) {
> - if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi))
> - raw_inode->i_version_hi =
> - cpu_to_le32(inode->i_version >> 32);
> - raw_inode->i_extra_isize = cpu_to_le16(ei->i_extra_isize);
> + if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
> + cpu_to_le32(EXT4_OS_HURD)) {
> + raw_inode->i_disk_version = cpu_to_le32(inode->i_version);
> + if (ei->i_extra_isize) {
> + if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi))
> + raw_inode->i_version_hi =
> + cpu_to_le32(inode->i_version >> 32);
> + raw_inode->i_extra_isize =
> + cpu_to_le16(ei->i_extra_isize);
> + }
> }
>
> ext4_inode_csum_set(inode, raw_inode, ei);
> --
> 1.9.0
>
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