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/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c
index 983718b..31b2d14 100644
--- a/drivers/nvdimm/btt.c
+++ b/drivers/nvdimm/btt.c
@@ -1210,7 +1210,7 @@
 	 * another kernel subsystem, and we just pass it through.
 	 */
 	if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
-		bio->bi_error = -EIO;
+		bio->bi_status = BLK_STS_IOERR;
 		goto out;
 	}
 
@@ -1232,7 +1232,7 @@
 					(op_is_write(bio_op(bio))) ? "WRITE" :
 					"READ",
 					(unsigned long long) iter.bi_sector, len);
-			bio->bi_error = err;
+			bio->bi_status = errno_to_blk_status(err);
 			break;
 		}
 	}