[PATCH 1/1] Btrfs: btrfs_release_super_kobj() should clean up the kobject data

[Anand Jain <anand.jain@oracle.com>]

The following test case which is a fair tweak with in the funcation
open_ctree() fails with an error from kobject module, indicating that
thread tried to init an initialized object.

kernel: [232104.016513] kobject (ffff880006c1c980): tried to init an initialized object, something is seriously wrong.

btrfs_sysfs_remove_one() self test code:

open_tree()
{
 ::
        ret = btrfs_sysfs_add_one(fs_info);
	if (ret) {
              pr_err("BTRFS: failed to init sysfs interface: %d\n", ret);
                goto fail_block_groups;
        }
+       btrfs_sysfs_remove_one(fs_info);
+       ret = btrfs_sysfs_add_one(fs_info);
+       if (ret) {
+               pr_err("BTRFS: failed to init sysfs interface: %d\n", ret);
+               goto fail_block_groups;
+       }

cleaning up the unregistered kobject fixes this.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/sysfs.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 92db3f6..68dcd17 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -439,6 +439,8 @@ static struct attribute *btrfs_attrs[] = {
 static void btrfs_release_super_kobj(struct kobject *kobj)
 {
 	struct btrfs_fs_info *fs_info = to_fs_info(kobj);
+
+	memset(&fs_info->super_kobj, 0, sizeof(struct kobject));
 	complete(&fs_info->kobj_unregister);
 }
 
-- 
2.0.0.153.g79dcccc