[PATCH 5.16 0749/1039] dm: fix alloc_dax error handling in alloc_dev

[Greg Kroah-Hartman]

From: Christoph Hellwig <hch@xxxxxx>

[ Upstream commit d751939235b9b7bc4af15f90a3e99288a8b844a7 ]

Make sure ->dax_dev is NULL on error so that the cleanup path doesn't
trip over an ERR_PTR.

Reported-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Link: https://lore.kernel.org/r/20211129102203.2243509-2-hch@xxxxxx
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/md/dm.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 662742a310cbb..acc84dc1bded5 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1786,8 +1786,10 @@ static struct mapped_device *alloc_dev(int minor)
 	if (IS_ENABLED(CONFIG_DAX_DRIVER)) {
 		md->dax_dev = alloc_dax(md, md->disk->disk_name,
 					&dm_dax_ops, 0);
-		if (IS_ERR(md->dax_dev))
+		if (IS_ERR(md->dax_dev)) {
+			md->dax_dev = NULL;
 			goto bad;
+		}
 	}
 
 	format_dev_t(md->name, MKDEV(_major, minor));
-- 
2.34.1