[PATCH 1/7] block: clear ->slave_dir when dropping the main slave_dir reference

From: Christoph Hellwig <hch@lst.de>
To: Jens Axboe <axboe@kernel.dk>, Alasdair Kergon <agk@redhat.com>,
	Mike Snitzer <snitzer@kernel.org>
Cc: Yu Kuai <yukuai1@huaweicloud.com>,
	dm-devel@redhat.com, linux-block@vger.kernel.org
Subject: [PATCH 1/7] block: clear ->slave_dir when dropping the main slave_dir reference
Date: Sun, 30 Oct 2022 16:31:13 +0100	[thread overview]
Message-ID: <20221030153120.1045101-2-hch@lst.de> (raw)
In-Reply-To: <20221030153120.1045101-1-hch@lst.de>

Zero out the pointer to ->slave_dir so that the holder code doesn't
incorrectly treat the object as alive when add_disk failed or after
del_gendisk was called.

Fixes: 89f871af1b26 ("dm: delay registering the gendisk")
Reported-by: Yu Kuai <yukuai1@huaweicloud.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/genhd.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/block/genhd.c b/block/genhd.c
index 17b33c62423df..aa0e2f5684543 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -528,6 +528,7 @@ int __must_check device_add_disk(struct device *parent, struct gendisk *disk,
 	blk_unregister_queue(disk);
 out_put_slave_dir:
 	kobject_put(disk->slave_dir);
+	disk->slave_dir = NULL;
 out_put_holder_dir:
 	kobject_put(disk->part0->bd_holder_dir);
 out_del_integrity:
@@ -624,6 +625,7 @@ void del_gendisk(struct gendisk *disk)
 
 	kobject_put(disk->part0->bd_holder_dir);
 	kobject_put(disk->slave_dir);
+	disk->slave_dir = NULL;
 
 	part_stat_set_all(disk->part0, 0);
 	disk->part0->bd_stamp = 0;
-- 
2.30.2

