block: don't return 1 for the fallback case in blkdev_get_zone_info

blkdev_do_report_zones returns the number of reported zones, but
blkdev_get_zone_info returns 0 or an errno.  Translate to the expected
return value in blkdev_report_zone_fallback.

Fixes: b037d41762fd ("block: introduce blkdev_get_zone_info()")
Signed-off-by: Christoph Hellwig <[email protected]>
Reviewed-by: Damien Le Moal <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

Author: Christoph Hellwig

block/blk-zoned.c

@@ -895,8 +895,14 @@ static int blkdev_report_zone_fallback(struct block_device *bdev,
 		.data = zone,
 		.report_active = true,
 	};
+	int error;
 
-	return blkdev_do_report_zones(bdev, sector, 1, &args);
+	error = blkdev_do_report_zones(bdev, sector, 1, &args);
+	if (error < 0)
+		return error;
+	if (error == 0)
+		return -EIO;
+	return 0;
 }
 
 /*