dm: only initialize md->dax_dev if CONFIG_DAX_DRIVER is enabled

md->dax_dev defaults to NULL and there is no need to initialize it
if CONFIG_DAX_DRIVER is disabled.

Signed-off-by: Peng Wang <rocking@whu.edu.cn>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 043f076..56c34a0 100644 (file)
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1906,7 +1906,6 @@ static void cleanup_mapped_device(struct mapped_device *md)
 static struct mapped_device *alloc_dev(int minor)
 {
        int r, numa_node_id = dm_get_numa_node();
-       struct dax_device *dax_dev = NULL;
        struct mapped_device *md;
        void *old_md;
 
@@ -1969,11 +1968,10 @@ static struct mapped_device *alloc_dev(int minor)
        sprintf(md->disk->disk_name, "dm-%d", minor);
 
        if (IS_ENABLED(CONFIG_DAX_DRIVER)) {
-               dax_dev = alloc_dax(md, md->disk->disk_name, &dm_dax_ops);
-               if (!dax_dev)
+               md->dax_dev = alloc_dax(md, md->disk->disk_name, &dm_dax_ops);
+               if (!md->dax_dev)
                        goto bad;
        }
-       md->dax_dev = dax_dev;
 
        add_disk_no_queue_reg(md->disk);
        format_dev_t(md->name, MKDEV(_major, minor));