Re: [PATCH] io_uring: don't mark S_ISBLK async work as unbounded

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

在 2021/4/1 下午10:57, Jens Axboe 写道:
> S_ISBLK is marked as unbounded work for async preparation, because it
> doesn't match S_ISREG. That is incorrect, as any read/write to a block
> device is also a bounded operation. Fix it up and ensure that S_ISBLK
> isn't marked unbounded.
> 
> Signed-off-by: Jens Axboe <axboe@kernel.dk>
> 
Hi Jens, I saw a (un)bounded work is for a (un)bounded worker to
execute. What is the difference between bounded and unbounded?

Thanks,
Hao
> ---
> 
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index 6d7a1b69712b..a16b7df934d1 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -1213,7 +1213,7 @@ static void io_prep_async_work(struct io_kiocb *req)
>   	if (req->flags & REQ_F_ISREG) {
>   		if (def->hash_reg_file || (ctx->flags & IORING_SETUP_IOPOLL))
>   			io_wq_hash_work(&req->work, file_inode(req->file));
> -	} else {
> +	} else if (!req->file || !S_ISBLK(file_inode(req->file)->i_mode)) {
>   		if (def->unbound_nonreg_file)
>   			req->work.flags |= IO_WQ_WORK_UNBOUND;
>   	}
>