Re: [PATCH 1/3] io_uring: flush completions for fallbacks

[Hao Xu <haoxu@linux.alibaba.com>]

在 2021/8/18 下午7:42, Pavel Begunkov 写道:
> io_fallback_req_func() doesn't expect anyone creating inline
> completions, and no one currently does that. Teach the function to flush
> completions preparing for further changes.
> 
> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
> ---
>   fs/io_uring.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index 3da9f1374612..ba087f395507 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -1197,6 +1197,11 @@ static void io_fallback_req_func(struct work_struct *work)
>   	percpu_ref_get(&ctx->refs);
>   	llist_for_each_entry_safe(req, tmp, node, io_task_work.fallback_node)
>   		req->io_task_work.func(req);
> +
> +	mutex_lock(&ctx->uring_lock);
> +	if (ctx->submit_state.compl_nr)
> +		io_submit_flush_completions(ctx);
> +	mutex_unlock(&ctx->uring_lock);
why do we protect io_submit_flush_completions() with uring_lock,
regarding that it is called in original context. Btw, why not
use ctx_flush_and_put()
>   	percpu_ref_put(&ctx->refs);
>   }
>   
>