Re: [PATCH for-5.10] io_uring: remove req cancel in ->flush()

[Jens Axboe <axboe@kernel.dk>]

On 10/19/20 9:45 AM, Pavel Begunkov wrote:
> Every close(io_uring) causes cancellation of all inflight requests
> carrying ->files. That's not nice but was neccessary up until recently.
> Now task->files removal is handled in the core code, so that part of
> flush can be removed.

It does change the behavior, but I'd wager that's safe. One minor
comment:

> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index 95d2bb7069c6..6536e24eb44e 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -8748,16 +8748,12 @@ void __io_uring_task_cancel(void)
>  
>  static int io_uring_flush(struct file *file, void *data)
>  {
> -	struct io_ring_ctx *ctx = file->private_data;
> +	bool exiting = !data;
>  
> -	/*
> -	 * If the task is going away, cancel work it may have pending
> -	 */
>  	if (fatal_signal_pending(current) || (current->flags & PF_EXITING))
> -		data = NULL;
> +		exiting = true;
>  
> -	io_uring_cancel_task_requests(ctx, data);
> -	io_uring_attempt_task_drop(file, !data);
> +	io_uring_attempt_task_drop(file, exiting);
>  	return 0;
>  }

Why not just keep the !data for task_drop? Would make the diff take
away just the hunk we're interested in. Even adding a comment would be
better, imho.

-- 
Jens Axboe