ocfs2: fix crash when initialize filecheck kobj fails

Once s_root is set, genric_shutdown_super() will be called if
fill_super() fails.  That means, we will call ocfs2_dismount_volume()
twice in such case, which can lead to kernel crash.

Fix this issue by initializing filecheck kobj before setting s_root.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: 5f483c4 ("ocfs2: add kobject for online file check")
Signed-off-by: Joseph Qi <[email protected]>
Cc: Mark Fasheh <[email protected]>
Cc: Joel Becker <[email protected]>
Cc: Junxiao Bi <[email protected]>
Cc: Changwei Ge <[email protected]>
Cc: Gang He <[email protected]>
Cc: Jun Piao <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

fs/ocfs2/super.c

@@ -1105,17 +1105,6 @@ static int ocfs2_fill_super(struct super_block *sb, void *data, int silent)
 		goto read_super_error;
 	}
 
-	root = d_make_root(inode);
-	if (!root) {
-		status = -ENOMEM;
-		mlog_errno(status);
-		goto read_super_error;
-	}
-
-	sb->s_root = root;
-
-	ocfs2_complete_mount_recovery(osb);
-
 	osb->osb_dev_kset = kset_create_and_add(sb->s_id, NULL,
 						&ocfs2_kset->kobj);
 	if (!osb->osb_dev_kset) {
@@ -1133,6 +1122,17 @@ static int ocfs2_fill_super(struct super_block *sb, void *data, int silent)
 		goto read_super_error;
 	}
 
+	root = d_make_root(inode);
+	if (!root) {
+		status = -ENOMEM;
+		mlog_errno(status);
+		goto read_super_error;
+	}
+
+	sb->s_root = root;
+
+	ocfs2_complete_mount_recovery(osb);
+
 	if (ocfs2_mount_local(osb))
 		snprintf(nodestr, sizeof(nodestr), "local");
 	else