[PATCH 3.18 21/21] dm io: fix duplicate bio completion due to missing ref count

3.18-stable review patch. If anyone has any objections, please let me know. -- From: Mike Snitzer commit feb7695fe9fb83084aa29de0094774f4c9d4c9fc upstream. If only a subset of the devices associated with multiple regions support a given special operation

[PATCH 3.18 21/21] dm io: fix duplicate bio completion due to missing ref count

3.18-stable review patch. If anyone has any objections, please let me know. -- From: Mike Snitzer commit feb7695fe9fb83084aa29de0094774f4c9d4c9fc upstream. If only a subset of the devices associated with multiple regions support a given special operation (eg. DISCARD) then