[PATCH 2/2] block: fix a race between del_gendisk and BLKRRPART

From: Christoph Hellwig <hch@lst.de>
To: axboe@kernel.dk
Cc: Gulam Mohamed <gulam.mohamed@oracle.com>,
	Ming Lei <ming.lei@redhat.com>,
	linux-block@vger.kernel.org
Subject: [PATCH 2/2] block: fix a race between del_gendisk and BLKRRPART
Date: Fri, 14 May 2021 15:18:42 +0200	[thread overview]
Message-ID: <20210514131842.1600568-3-hch@lst.de> (raw)
In-Reply-To: <20210514131842.1600568-1-hch@lst.de>

From: Gulam Mohamed <gulam.mohamed@oracle.com>

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>
---
 fs/block_dev.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 580bae995b87..4494411fa4d3 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1244,6 +1244,9 @@ 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:
 	if (bdev->bd_part_count)
 		return -EBUSY;
-- 
2.30.2

