linux-kernel - Re: s390 boot woe due to "block: fix busy device checking in blk_drop

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Message-ID: <20200410054544.GA17923@lst.de>
Date:   Fri, 10 Apr 2020 07:45:44 +0200
From:   Christoph Hellwig <hch@....de>
To:     Qian Cai <cai@....pw>
Cc:     Christoph Hellwig <hch@....de>, Jens Axboe <axboe@...nel.dk>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        linux-block@...r.kernel.org, linux-s390@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: s390 boot woe due to "block: fix busy device checking in
 blk_drop_partitions"

Please try this patch:

---
>From f42fb98cc627f9b960fd5b9a3a229da5c5dcf54a Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@....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@....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