Revision 1:
  kgdb

Revision 2:
  When setting the size of a Device-Mapper device in the gendisk entry,
  also try to set the size of the corresponding block_device entry's
  inode. This is necessary to allow online device/filesystem resizing to
  work correctly.  [Kevin Corry]

Revision 3:
  The dm table size is always known in advance, so we can specify it in
  dm_table_create(), rather than relying on dynamic resizing.

Revision 4:
  Make the version-4 ioctl interface the default kernel configuration option.

Revision 5:
  Experimental version of the snapshot and mirror targets for 2.6.

Revision 6:
  Take a space out of a slab name.

Revision 7:
  take note of the tio->io field before freeing tio.

Revision 8:
  A blk_put_queue() was missing on the error path of alloc_dev().

Revision 9:
  whitespace

Revision 10:
  Set the split io size for the snapshot target.

Revision 11:
  Enable the new code that checks that an exception isn't already being copied.

Revision 12:
  Recheck that the exception hasn't entered the pending table by another
  thread.

Revision 13:
  Set the ti->split_io field for the origin to the smallest chunk-size of its
  snapshots. This is done each time the origin is resumed, since new snapshots
  (with smaller chunk-sizes) could have been added.  [Kevin Corry]

Revision 14:
  In the "else" section of __clone_and_map(), we're splitting a page from the
  bio into two pages and mapping each part separately. Therefore, we need
  another tio structure to track the second part of the page.  [Kevin Corry]

Revision 15:
  In order to properly build snapshot as its own kernel module,
  dm-snapshot.c and dm-snapshot.h must be renamed to dm-snap.c and
  dm-snap.h. The dm_vcalloc function must also be exported from
  dm-table.c so the snapshot module can find it.  [Kevin Corry]