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/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 9684585..ea9f455 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -749,7 +749,7 @@ static void f2fs_submit_discard_endio(struct bio *bio)
 {
 	struct discard_cmd *dc = (struct discard_cmd *)bio->bi_private;
 
-	dc->error = bio->bi_error;
+	dc->error = blk_status_to_errno(bio->bi_status);
 	dc->state = D_DONE;
 	complete(&dc->wait);
 	bio_put(bio);