Taka's fix for handling failure of all mirrored log devices and

Taka's fix for handling failure of all mirrored log devices and
all but one mirror leg.

<patch header>
To handle a double failure of a mirrored log, Jon's two patches are
commited, however, lvconvert command can't still handle an error
when mirror leg and mirrored log got failure at the same time.

  [Patch]: Handle both devices of a mirrored log failing (bug 607347)
  posted: https://www.redhat.com/archives/lvm-devel/2010-July/msg00009.html
  commit: https://www.redhat.com/archives/lvm-devel/2010-July/msg00027.html

  [Patch]: Handle both devices of a mirrored log failing (bug 607347) -
           additional fix
  posted: https://www.redhat.com/archives/lvm-devel/2010-July/msg00093.html
  commit: https://www.redhat.com/archives/lvm-devel/2010-July/msg00101.html

In the second patch, the target type of mirrored log is replaced with
error target when remove_log is set to 1, but this procedure should be
also used in other cases such as the number of mirror leg is 1. This
patch relocates the procedure to the main path.

In addition, I added following three changes.

- Removed tmp_orphan_lvs handling procedure
  It seems that _delete_lv() can handle detached_log_lv properly
  without adding mirror legs in mirrored log to tmp_orphan_lvs.
  Therefore, I removed the procedure.

- Removed vg_write()/vg_commit()
  Metadata is saved by vg_write()/vg_commit() just after detached_log_lv
  is handled. Therefore, I removed vg_write()/vg_commit().

- With Jon's second patch, we think that we don't have to call
  remove_mirror_log() in _lv_update_mirrored_log() because will be
  handled remove_mirror_images() in _lvconvert_mirrors_repaire().
</patch header>

Signed-off-by: Takahiro Yasui <takahiro.yasui@hds.com>
Reviewed-by: Petr Rockai <prockai@redhat.com>
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>