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From: Jens Axboe <axboe@kernel.dk>
To: adam.manzanares@wdc.com, viro@zeniv.linux.org.uk,
	linux-fsdevel@vger.kernel.org, bcrl@kvack.org
Cc: mingo@kernel.org, peterz@infradead.org, pombredanne@nexb.com,
	gregkh@linuxfoundation.org, bigeasy@linutronix.de,
	rgoldwyn@suse.com, linux-block@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-aio@kvack.org,
	linux-api@vger.kernel.org
Subject: Re: [PATCH v4 3/3] fs: Add aio iopriority support for block_dev
Date: Fri, 18 May 2018 09:14:07 -0600	[thread overview]
Message-ID: <51cbf2e9-1ff9-b9e7-fb68-055a64d54da5@kernel.dk> (raw)
In-Reply-To: <20180517203803.2664-4-adam.manzanares@wdc.com>

On 5/17/18 2:38 PM, adam.manzanares@wdc.com wrote:
> From: Adam Manzanares <adam.manzanares@wdc.com>
> 
> This is the per-I/O equivalent of the ioprio_set system call.
> 
> When IOCB_FLAG_IOPRIO is set on the iocb aio_flags field, then we set the
> newly added kiocb ki_ioprio field to the value in the iocb aio_reqprio field.
> 
> When a bio is created for an aio request by the block dev we set the priority
> value of the bio to the user supplied value.
> 
> This patch depends on block: add ioprio_check_cap function

Actually, one comment on this one:

> diff --git a/fs/aio.c b/fs/aio.c
> index f3eae5d5771b..ff3107aa82d5 100644
> --- a/fs/aio.c
> +++ b/fs/aio.c
> @@ -1451,6 +1451,22 @@ static int aio_prep_rw(struct kiocb *req, struct iocb *iocb)
>  	if (iocb->aio_flags & IOCB_FLAG_RESFD)
>  		req->ki_flags |= IOCB_EVENTFD;
>  	req->ki_hint = file_write_hint(req->ki_filp);
> +	if (iocb->aio_flags & IOCB_FLAG_IOPRIO) {
> +		/*
> +		 * If the IOCB_FLAG_IOPRIO flag of aio_flags is set, then
> +		 * aio_reqprio is interpreted as an I/O scheduling
> +		 * class and priority.
> +		 */
> +		ret = ioprio_check_cap(iocb->aio_reqprio);
> +		if (ret) {
> +			pr_debug("aio ioprio check cap error\n");
> +			return -EINVAL;
> +		}
> +
> +		req->ki_ioprio = iocb->aio_reqprio;
> +		req->ki_flags |= IOCB_IOPRIO;
> +	}

Do we really need IOCB_IOPRIO? All zeroes is no priority set anyway,
so we should be able to get by with just setting ->ki_ioprio to either
the priority, or 0.

> diff --git a/fs/block_dev.c b/fs/block_dev.c
> index 7ec920e27065..970bef79caa6 100644
> --- a/fs/block_dev.c
> +++ b/fs/block_dev.c
> @@ -355,6 +355,8 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
>  		bio->bi_write_hint = iocb->ki_hint;
>  		bio->bi_private = dio;
>  		bio->bi_end_io = blkdev_bio_end_io;
> +		if (iocb->ki_flags & IOCB_IOPRIO)
> +			bio->bi_ioprio = iocb->ki_ioprio;

And then this assignment can just happen unconditionally.

-- 
Jens Axboe

  reply	other threads:[~2018-05-18 15:14 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-17 20:38 [PATCH v4 0/3] AIO add per-command iopriority adam.manzanares
2018-05-17 20:38 ` [PATCH v4 1/3] block: add ioprio_check_cap function adam.manzanares
2018-05-18 16:04   ` Christoph Hellwig
2018-05-17 20:38 ` [PATCH v4 2/3] fs: Convert kiocb rw_hint from enum to u16 adam.manzanares
2018-05-18 16:05   ` Christoph Hellwig
2018-05-18 19:53     ` Adam Manzanares
2018-05-17 20:38 ` [PATCH v4 3/3] fs: Add aio iopriority support for block_dev adam.manzanares
2018-05-18 15:14   ` Jens Axboe [this message]
2018-05-18 15:29     ` Adam Manzanares
2018-05-18 16:06   ` Christoph Hellwig
2018-05-18 19:54     ` Adam Manzanares
2018-05-18 20:08   ` kbuild test robot
2018-05-18  2:41 ` [PATCH v4 0/3] AIO add per-command iopriority Jens Axboe
2018-05-18 15:03   ` Adam Manzanares

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