[dm-devel] Should enhanced bio error state be propagated upwards to parent o f failed cloned bios?

["goggin, edward" <egoggin emc com>]

Should the bi_error field of a failed bio clone completion be propagated
upwards into the parent of the cloned bio, possibly in dec_pending() of
dm.c?  Doing so will allow target drivers higher than the one managing
the bottom-most mapped device to have access to enhanced bio sense
and error information.  Otherwise, all they see is -EIO like now.