ext4: simplify kobject usage

Replace kset with generic kobject provided by kobject_create_and_add(),
since the latter is sufficient.
Signed-off-by: Tyson Nottingham <tgnottingham@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/sysfs.c

@@ -325,13 +325,6 @@ static void ext4_sb_release(struct kobject *kobj)
 	complete(&sbi->s_kobj_unregister);
 }
 
-static void ext4_kset_release(struct kobject *kobj)
-{
-	struct kset *kset = container_of(kobj, struct kset, kobj);
-
-	kfree(kset);
-}
-
 static const struct sysfs_ops ext4_attr_ops = {
 	.show	= ext4_attr_show,
 	.store	= ext4_attr_store,
@@ -343,19 +336,14 @@ static struct kobj_type ext4_sb_ktype = {
 	.release	= ext4_sb_release,
 };
 
-static struct kobj_type ext4_ktype = {
-	.sysfs_ops	= &ext4_attr_ops,
-	.release	= ext4_kset_release,
-};
-
-static struct kset *ext4_kset;
-
 static struct kobj_type ext4_feat_ktype = {
 	.default_attrs	= ext4_feat_attrs,
 	.sysfs_ops	= &ext4_attr_ops,
 	.release	= (void (*)(struct kobject *))kfree,
 };
 
+static struct kobject *ext4_root;
+
 static struct kobject *ext4_feat;
 
 #define PROC_FILE_SHOW_DEFN(name) \
@@ -393,9 +381,8 @@ int ext4_register_sysfs(struct super_block *sb)
 	const struct ext4_proc_files *p;
 	int err;
 
-	sbi->s_kobj.kset = ext4_kset;
 	init_completion(&sbi->s_kobj_unregister);
-	err = kobject_init_and_add(&sbi->s_kobj, &ext4_sb_ktype, NULL,
+	err = kobject_init_and_add(&sbi->s_kobj, &ext4_sb_ktype, ext4_root,
 				   "%s", sb->s_id);
 	if (err) {
 		kobject_put(&sbi->s_kobj);
@@ -431,26 +418,18 @@ int __init ext4_init_sysfs(void)
 {
 	int ret;
 
-	ext4_kset = kzalloc(sizeof(*ext4_kset), GFP_KERNEL);
-	if (!ext4_kset)
+	ext4_root = kobject_create_and_add("ext4", fs_kobj);
+	if (!ext4_root)
 		return -ENOMEM;
 
-	kobject_set_name(&ext4_kset->kobj, "ext4");
-	ext4_kset->kobj.parent = fs_kobj;
-	ext4_kset->kobj.ktype = &ext4_ktype;
-	ret = kset_register(ext4_kset);
-	if (ret)
-		goto kset_err;
-
 	ext4_feat = kzalloc(sizeof(*ext4_feat), GFP_KERNEL);
 	if (!ext4_feat) {
 		ret = -ENOMEM;
-		goto kset_err;
+		goto root_err;
 	}
 
-	ext4_feat->kset = ext4_kset;
 	ret = kobject_init_and_add(ext4_feat, &ext4_feat_ktype,
-				   NULL, "features");
+				   ext4_root, "features");
 	if (ret)
 		goto feat_err;
 
@@ -460,9 +439,9 @@ int __init ext4_init_sysfs(void)
 feat_err:
 	kobject_put(ext4_feat);
 	ext4_feat = NULL;
-kset_err:
-	kset_unregister(ext4_kset);
-	ext4_kset = NULL;
+root_err:
+	kobject_put(ext4_root);
+	ext4_root = NULL;
 	return ret;
 }
 
@@ -470,8 +449,8 @@ void ext4_exit_sysfs(void)
 {
 	kobject_put(ext4_feat);
 	ext4_feat = NULL;
-	kset_unregister(ext4_kset);
-	ext4_kset = NULL;
+	kobject_put(ext4_root);
+	ext4_root = NULL;
 	remove_proc_entry(proc_dirname, NULL);
 	ext4_proc_root = NULL;
 }