dm: introduce a new DM_MAPIO_KILL return value

This untangles the DM_MAPIO_* values returned from ->clone_and_map_rq
from the error codes used by the block layer.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 5a02fc0..78ad062 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -604,6 +604,7 @@ extern struct ratelimit_state dm_ratelimit_state;
 #define DM_MAPIO_REMAPPED	1
 #define DM_MAPIO_REQUEUE	DM_ENDIO_REQUEUE
 #define DM_MAPIO_DELAY_REQUEUE	3
+#define DM_MAPIO_KILL		4
 
 #define dm_sector_div64(x, y)( \
 { \