This patch contains the changes to support 48-bit block numbers in extents.
This patch is not complete, the new function block_iterate_extents() was
not updated.

  e2fsck/pass1.c            |   15 +++++++++------
  lib/ext2fs/bmap.c         |    9 +++++----
  lib/ext2fs/ext3_extents.h |   28 ++++++++++++++++++++++++++++
  lib/ext2fs/extent.c       |   23 +++++++++++------------
  4 files changed, 53 insertions(+), 22 deletions(-)