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Date:   Wed, 2 May 2018 10:33:22 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     adam.manzanares@wdc.com
Cc:     viro@zeniv.linux.org.uk, bcrl@kvack.org,
        linux-fsdevel@vger.kernel.org, linux-aio@kvack.org,
        linux-abi-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] fs: Add aio priority support for block_dev
Message-ID: <20180502173322.GB27997@infradead.org>
References: <20180430165740.2842-1-adam.manzanares@wdc.com>
 <20180430165740.2842-3-adam.manzanares@wdc.com>
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> --- a/fs/aio.c
> +++ b/fs/aio.c
> @@ -1603,6 +1603,15 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
>  		goto out_put_req;
>  	}
>  
> +	if (req->common.ki_flags & IOCB_IOPRIO)
> +		/*
> +		 * The IOCB_IOPRIO flag is set when the user supplied iocb
> +		 * aio_rw_flag field has the RWF_IOPRIO flag set. If so,
> +		 * aio_reqprio is interpreted as a I/O scheduling class and
> +		 * priority.
> +		 */
> +		req->common.ki_ioprio = iocb->aio_reqprio;

Do we need any validation of the field here?

The only other thing I am a bit worried about is bloating struct kiocb
with a field for a relatively uncommon feature, but I can't really
see any much better way to pass it.