block: switch bios to blk_status_t

Replace bi_error with a new bi_status to allow for a clear conversion.
Note that device mapper overloaded bi_error with a private value, which
we'll have to keep arround at least for now and thus propagate to a
proper blk_status_t value.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 5de5c53..456da50 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -72,7 +72,7 @@ typedef void (*dm_release_clone_request_fn) (struct request *clone);
  * 2   : The target wants to push back the io
  */
 typedef int (*dm_endio_fn) (struct dm_target *ti,
-			    struct bio *bio, int *error);
+			    struct bio *bio, blk_status_t *error);
 typedef int (*dm_request_endio_fn) (struct dm_target *ti,
 				    struct request *clone, blk_status_t error,
 				    union map_info *map_context);