[PATCH 0 of 2] imporoved mirror DSO logging

This patchset consists of two patches. Patch 1 just logs better error
messages. Patch 2 [RFC] attempts to re-integrate a failed secondary mirror
device [the second patch required a minor dm-raid1 module patch for testing].

Signed-off-by: Malahal Naineni (malahal at us.ibm.com)

Thanks, Malahal.