dm: don't return errnos from ->map

Instead use the special DM_MAPIO_KILL return value to return -EIO just
like we do for the request based path.  Note that dm-log-writes returned
-ENOMEM in a few places, which now becomes -EIO instead.  No consumer
treats -ENOMEM special so this shouldn't be an issue (and it should
use a mempool to start with to make guaranteed progress).

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c
index 5e30b08..d9c0c6a 100644
--- a/drivers/md/dm-raid1.c
+++ b/drivers/md/dm-raid1.c
@@ -1207,14 +1207,14 @@ static int mirror_map(struct dm_target *ti, struct bio *bio)
 
 	r = log->type->in_sync(log, dm_rh_bio_to_region(ms->rh, bio), 0);
 	if (r < 0 && r != -EWOULDBLOCK)
-		return r;
+		return DM_MAPIO_KILL;
 
 	/*
 	 * If region is not in-sync queue the bio.
 	 */
 	if (!r || (r == -EWOULDBLOCK)) {
 		if (bio->bi_opf & REQ_RAHEAD)
-			return -EIO;
+			return DM_MAPIO_KILL;
 
 		queue_bio(ms, bio, rw);
 		return DM_MAPIO_SUBMITTED;
@@ -1226,7 +1226,7 @@ static int mirror_map(struct dm_target *ti, struct bio *bio)
 	 */
 	m = choose_mirror(ms, bio->bi_iter.bi_sector);
 	if (unlikely(!m))
-		return -EIO;
+		return DM_MAPIO_KILL;
 
 	dm_bio_record(&bio_record->details, bio);
 	bio_record->m = m;