linux-kernel - Re: [PATCH v4 02/11] block: Call blkdev_dio_unaligned() from blkdev_direct

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Message-ID: <ZdOklTSG9tHuYtGi@kbusch-mbp>
Date: Mon, 19 Feb 2024 11:57:25 -0700
From: Keith Busch <kbusch@...nel.org>
To: John Garry <john.g.garry@...cle.com>
Cc: axboe@...nel.dk, hch@....de, sagi@...mberg.me, jejb@...ux.ibm.com,
	martin.petersen@...cle.com, djwong@...nel.org,
	viro@...iv.linux.org.uk, brauner@...nel.org, dchinner@...hat.com,
	jack@...e.cz, linux-block@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-nvme@...ts.infradead.org,
	linux-fsdevel@...r.kernel.org, tytso@....edu, jbongio@...gle.com,
	linux-scsi@...r.kernel.org, ojaswin@...ux.ibm.com,
	linux-aio@...ck.org, linux-btrfs@...r.kernel.org,
	io-uring@...r.kernel.org, nilay@...ux.ibm.com,
	ritesh.list@...il.com
Subject: Re: [PATCH v4 02/11] block: Call blkdev_dio_unaligned() from
 blkdev_direct_IO()

On Mon, Feb 19, 2024 at 01:01:00PM +0000, John Garry wrote:
> @@ -53,9 +53,6 @@ static ssize_t __blkdev_direct_IO_simple(struct kiocb *iocb,
>  	struct bio bio;
>  	ssize_t ret;
>  
> -	if (blkdev_dio_unaligned(bdev, pos, iter))
> -		return -EINVAL;
> -
>  	if (nr_pages <= DIO_INLINE_BIO_VECS)
>  		vecs = inline_vecs;
>  	else {
> @@ -171,9 +168,6 @@ static ssize_t __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
>  	loff_t pos = iocb->ki_pos;
>  	int ret = 0;
>  
> -	if (blkdev_dio_unaligned(bdev, pos, iter))
> -		return -EINVAL;
> -
>  	if (iocb->ki_flags & IOCB_ALLOC_CACHE)
>  		opf |= REQ_ALLOC_CACHE;
>  	bio = bio_alloc_bioset(bdev, nr_pages, opf, GFP_KERNEL,
> @@ -310,9 +304,6 @@ static ssize_t __blkdev_direct_IO_async(struct kiocb *iocb,
>  	loff_t pos = iocb->ki_pos;
>  	int ret = 0;
>  
> -	if (blkdev_dio_unaligned(bdev, pos, iter))
> -		return -EINVAL;
> -
>  	if (iocb->ki_flags & IOCB_ALLOC_CACHE)
>  		opf |= REQ_ALLOC_CACHE;
>  	bio = bio_alloc_bioset(bdev, nr_pages, opf, GFP_KERNEL,
> @@ -365,11 +356,16 @@ static ssize_t __blkdev_direct_IO_async(struct kiocb *iocb,
>  
>  static ssize_t blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
>  {
> +	struct block_device *bdev = I_BDEV(iocb->ki_filp->f_mapping->host);
> +	loff_t pos = iocb->ki_pos;
>  	unsigned int nr_pages;

All three of the changed functions also want 'bdev' and 'pos', so maybe
pass on the savings to them? Unless you think the extended argument list
would harm readibilty, or perhaps the compiler optimizes the 2nd access
out anyway. Either way, this looks good to me.

Reviewed-by: Keith Busch <kbusch@...nel.org>