Re: s390 boot woe due to "block: fix busy device checking in blk_drop_partitions"

[Christoph Hellwig <hch@lst.de>]

Please try this patch:

---
From f42fb98cc627f9b960fd5b9a3a229da5c5dcf54a Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@lst.de>
Date: Fri, 10 Apr 2020 07:14:13 +0200
Subject: block: fix busy device checking in blk_drop_partitions again

The previous fix had an off by one in the bd_openers checking, counting
the callers blkdev_get.

Fixes: d3ef5536274f ("block: fix busy device checking in blk_drop_partitions")
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/partitions/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/partitions/core.c b/block/partitions/core.c
index 1a0a829d8416..bc1ded1331b1 100644
--- a/block/partitions/core.c
+++ b/block/partitions/core.c
@@ -496,7 +496,7 @@ int blk_drop_partitions(struct gendisk *disk, struct block_device *bdev)
 
 	if (!disk_part_scan_enabled(disk))
 		return 0;
-	if (bdev->bd_part_count || bdev->bd_openers)
+	if (bdev->bd_part_count || bdev->bd_openers > 1)
 		return -EBUSY;
 	res = invalidate_partition(disk, 0);
 	if (res)
-- 
2.25.1