linux-kernel - Re: [PATCH] iomap: directly use logical block size

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Date:   Wed, 26 Oct 2022 11:33:03 -0700
From:   "Darrick J. Wong" <djwong@...nel.org>
To:     Keith Busch <kbusch@...a.com>
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        hch@....de, bvanassche@....org, Keith Busch <kbusch@...nel.org>
Subject: Re: [PATCH] iomap: directly use logical block size

On Wed, Oct 26, 2022 at 09:51:33AM -0700, Keith Busch wrote:
> From: Keith Busch <kbusch@...nel.org>
> 
> Don't transform the logical block size to a bit shift only to shift it
> back to the original block size. Just use the size.
> 
> Signed-off-by: Keith Busch <kbusch@...nel.org>
> ---
>  fs/iomap/direct-io.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
> index 4eb559a16c9e..503b97e5a115 100644
> --- a/fs/iomap/direct-io.c
> +++ b/fs/iomap/direct-io.c
> @@ -240,7 +240,7 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter,
>  {
>  	const struct iomap *iomap = &iter->iomap;
>  	struct inode *inode = iter->inode;
> -	unsigned int blkbits = blksize_bits(bdev_logical_block_size(iomap->bdev));
> +	unsigned int blksz = bdev_logical_block_size(iomap->bdev);

/me looks at what blksize_bits does (assumes block size > 256) and rolls
his eyes.

Regardless, this looks correct to me, so

Reviewed-by: Darrick J. Wong <djwong@...nel.org>

--D


>  	unsigned int fs_block_size = i_blocksize(inode), pad;
>  	loff_t length = iomap_length(iter);
>  	loff_t pos = iter->pos;
> @@ -252,7 +252,7 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter,
>  	size_t copied = 0;
>  	size_t orig_count;
>  
> -	if ((pos | length) & ((1 << blkbits) - 1) ||
> +	if ((pos | length) & (blksz - 1) ||
>  	    !bdev_iter_is_aligned(iomap->bdev, dio->submit.iter))
>  		return -EINVAL;
>  
> -- 
> 2.30.2
>