Btrfs: fix possible memory leaks in open_ctree()

Fix possible memory leaks in the following error handling paths:

read_tree_block()
btrfs_recover_log_trees
btrfs_commit_super()
btrfs_find_orphan_roots()
btrfs_cleanup_fs_roots()
Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>

fs/btrfs/disk-io.c

@@ -2864,7 +2864,7 @@ int open_ctree(struct super_block *sb,
 			printk(KERN_ERR "BTRFS: failed to read log tree\n");
 			free_extent_buffer(log_tree_root->node);
 			kfree(log_tree_root);
-			goto fail_trans_kthread;
+			goto fail_qgroup;
 		}
 		/* returns with log_tree_root freed on success */
 		ret = btrfs_recover_log_trees(log_tree_root);
@@ -2873,24 +2873,24 @@ int open_ctree(struct super_block *sb,
 				    "Failed to recover log tree");
 			free_extent_buffer(log_tree_root->node);
 			kfree(log_tree_root);
-			goto fail_trans_kthread;
+			goto fail_qgroup;
 		}
 
 		if (sb->s_flags & MS_RDONLY) {
 			ret = btrfs_commit_super(tree_root);
 			if (ret)
-				goto fail_trans_kthread;
+				goto fail_qgroup;
 		}
 	}
 
 	ret = btrfs_find_orphan_roots(tree_root);
 	if (ret)
-		goto fail_trans_kthread;
+		goto fail_qgroup;
 
 	if (!(sb->s_flags & MS_RDONLY)) {
 		ret = btrfs_cleanup_fs_roots(fs_info);
 		if (ret)
-			goto fail_trans_kthread;
+			goto fail_qgroup;
 
 		ret = btrfs_recover_relocation(tree_root);
 		if (ret < 0) {