On Jul 10, 2007 16:30 -0700, Andrew Morton wrote:
> > Signed-off-by: Mingming Cao <[EMAIL PROTECTED]>
> > Signed-off-by: Andreas Dilger <[EMAIL PROTECTED]>
> > Signed-off-by: Kalpak Shah <[EMAIL PROTECTED]>
> > ---
> > Index: linux-2.6.21/include/linux/ext4_fs.h
> > ===================================================================
> > --- linux-2.6.21.orig/include/linux/ext4_fs.h
> > +++ linux-2.6.21/include/linux/ext4_fs.h
> > @@ -342,6 +342,7 @@ struct ext4_inode {
> > __le32 i_atime_extra; /* extra Access time (nsec << 2 | epoch) */
> > __le32 i_crtime; /* File Creation time */
> > __le32 i_crtime_extra; /* extra FileCreationtime (nsec << 2 | epoch) */
> > + __le32 i_version_hi; /* high 32 bits for 64-bit version */
> > };
>
> Aren't there forward- backward-compatibility issues here? How does the
> filesystem driver work out whether this field is present and valid?
This uses the same EXT4_FITS_IN_INODE() check as any other, so the
compatibility issues are handled. NFSv4 could live with 32-bit versions
with only a small danger of overflow, so we can still export ext3
filesystems with 128-byte inodes that have been updated to ext4. For
Lustre (which requires 64-bit versions), we will enforce that space is
available with s_min_extra_isize and RO_COMPAT_EXTRA_ISIZE.
In the case where an older ext3/ext4 filesystem with large inodes does
not have enough space for i_version_hi the EAs that follow i_extra_isize
will be shifted to make room for it (if possible, which is likely). There
are no critical fields inside i_extra_isize so in the rare case of a
failure to enlarge the i_extra_isize is not a cause for alarm.
Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
