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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Gulam Mohamed <gulam.mohamed@oracle.com>,
        Christoph Hellwig <hch@lst.de>, Ming Lei <ming.lei@redhat.com>,
        Jens Axboe <axboe@kernel.dk>, Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.10 187/252] block: fix a race between del_gendisk and BLKRRPART
Date:   Mon, 31 May 2021 15:14:12 +0200
Message-Id: <20210531130704.362107639@linuxfoundation.org>
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From: Gulam Mohamed <gulam.mohamed@oracle.com>

[ Upstream commit bc6a385132601c29a6da1dbf8148c0d3c9ad36dc ]

When BLKRRPART is called concurrently with del_gendisk, the partitions
rescan can create a stale partition that will never be be cleaned up.

Fix this by checking the the disk is up before rescanning partitions
while under bd_mutex.

Signed-off-by: Gulam Mohamed <gulam.mohamed@oracle.com>
[hch: split from a larger patch]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20210514131842.1600568-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/block_dev.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index cacea6bafc22..29f020c4b2d0 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1408,6 +1408,9 @@ int bdev_disk_changed(struct block_device *bdev, bool invalidate)
 
 	lockdep_assert_held(&bdev->bd_mutex);
 
+	if (!(disk->flags & GENHD_FL_UP))
+		return -ENXIO;
+
 rescan:
 	ret = blk_drop_partitions(bdev);
 	if (ret)
-- 
2.30.2