[CRIU] [PATCH v7 06/15] files: new "used" files list introduced

[Pavel Emelyanov]

On 03/14/2016 05:59 PM, Stanislav Kinsburskiy wrote:
> This list contains all per-process used file fdinfo's, sorted by fd number.
> Will be used to safely create new artificial file descriptors and also allow
> to recreate temporary descriptors with original number, if possible, like
> AutoFS tries to preserve original pipe write end descriptor, when it was
> closed.
> This patch also adds simple helper to find unused file descriptor.
> Return "hint" if unused or last used descriptor plus one.

I finally got what's bad with this patch -- the fact that you put collect_used_fd
into all the ->collect_fd callbacks. This is dangerous as one more such callback
and the whole logic gets broken.

Plz, call the collect_used_fd in the core fd collecting routine, in the files.c's
collect_fd() one.

> +static inline void collect_used_fd(struct fdinfo_list_entry *new_fle, struct rst_info *ri)
> +{
> +	struct fdinfo_list_entry *fle;
> +
> +	list_for_each_entry(fle, &ri->used, used_list) {

You scan this list FULLY in find_unused_fd anyway, why keeping it sorted?

> +		if (new_fle->fe->fd < fle->fe->fd)
> +			break;
> +	}
> +
> +	list_add_tail(&new_fle->used_list, &fle->used_list);
> +}
> +