Now that alloc_dax() returns ERR_PTR(-EOPNOTSUPP) rather than NULL,
the callers do not have to handle NULL return values anymore.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Mike Snitzer <snitzer@kernel.org>
Cc: Mikulas Patocka <mpatocka@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Russell King <linux@armlinux.org.uk>
Cc: linux-arch@vger.kernel.org
Cc: linux-cxl@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: linux-xfs@vger.kernel.org
Cc: dm-devel@lists.linux.dev
Cc: nvdimm@lists.linux.dev
---
 drivers/md/dm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 2fc22cae9089..acdc00bc05be 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -2124,8 +2124,8 @@ static struct mapped_device *alloc_dev(int minor)
 	sprintf(md->disk->disk_name, "dm-%d", minor);
 
 	dax_dev = alloc_dax(md, &dm_dax_ops);
-	if (IS_ERR_OR_NULL(dax_dev)) {
-		if (IS_ERR(dax_dev) && PTR_ERR(dax_dev) != -EOPNOTSUPP)
+	if (IS_ERR(dax_dev)) {
+		if (PTR_ERR(dax_dev) != -EOPNOTSUPP)
 			goto bad;
 	} else {
 		set_dax_nocache(dax_dev);
-- 
2.39.2