[CRIU] [PATCH 2/4] files: resort code about dumping file descriptors

[Pavel Emelyanov]

> @@ -1203,20 +1168,6 @@ static int dump_one_task(struct pstree_item *item)
>  		goto err;
>  	}
>  
> -	if (!shared_fdtable(item)) {
> -		dfds = xmalloc(sizeof(*dfds));
> -		if (!dfds)
> -			goto err;
> -
> -		ret = collect_fds(pid, dfds);
> -		if (ret) {
> -			pr_err("Collect fds (pid: %d) failed with %d\n", pid, ret);
> -			goto err;
> -		}
> -
> -		parasite_ensure_args_size(drain_fds_size(dfds));
> -	}

What's wrong in collecting the descriptors early? In this place we _are_ sure
that the fds we see are those we need to dump.

> -
>  	ret = parse_posix_timers(pid, &proc_args);
>  	if (ret < 0) {
>  		pr_err("Can't read posix timers file (pid: %d)\n", pid);

> +int dump_task_files_seized(struct parasite_ctl *ctl, struct pstree_item *item)
> +{
> +	struct parasite_drain_fd *dfds = NULL;
> +	struct fd_opts *opts = NULL;
> +	struct cr_img *img = NULL;
> +	pid_t pid = ctl->pid.real;
> +	int *lfds = NULL;
>  	int i, ret = -1;
>  
>  	pr_info("\n");
>  	pr_info("Dumping opened files (pid: %d)\n", ctl->pid.real);
>  	pr_info("----------------------------------------\n");
>  
> +	dfds = xmalloc(sizeof(*dfds));
> +	if (!dfds)
> +		goto err;
> +
> +	img = open_image(CR_FD_FDINFO, O_DUMP, item->ids->files_id);
> +	if (!img)
> +		goto err;
> +
> +	ret = collect_fds(pid, dfds, (int [2]) {ctl->ptsock, ctl->plogfd} , 2);
> +	if (ret) {
> +		pr_err("Collect fds (pid: %d) failed with %d\n", pid, ret);
> +		goto err;
> +	}
> +
> +	parasite_ensure_args_size(drain_fds_size(dfds));

It's too late to ensure_args_size() here, the parasite is already injected.

> +
>  	lfds = xmalloc(dfds->nr_fds * sizeof(int));
>  	if (!lfds)
>  		goto err;
>  
>  	opts = xmalloc(dfds->nr_fds * sizeof(struct fd_opts));
>  	if (!opts)
> -		goto err1;
> +		goto err;
>  
>  	ret = parasite_drain_fds_seized(ctl, dfds, lfds, opts);
>  	if (ret)
> -		goto err2;
> -
> -	img = open_image(CR_FD_FDINFO, O_DUMP, item->ids->files_id);
> -	if (!img)
> -		goto err2;
> +		goto err;
>  
>  	for (i = 0; i < dfds->nr_fds; i++) {
>  		ret = dump_one_file(ctl, dfds->fds[i], lfds[i], opts + i, img);