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Date: Mon, 18 Nov 2024 08:08:05 +0100
From: Christoph Hellwig <hch@lst.de>
To: Luis Chamberlain <mcgrof@kernel.org>
Cc: willy@infradead.org, hch@lst.de, hare@suse.de, david@fromorbit.com,
	djwong@kernel.org, john.g.garry@oracle.com, ritesh.list@gmail.com,
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	linux-xfs@vger.kernel.org, linux-mm@kvack.org,
	linux-block@vger.kernel.org, gost.dev@samsung.com,
	p.raghav@samsung.com, da.gomez@samsung.com, kernel@pankajraghav.com
Subject: Re: [RFC 8/8] bdev: use bdev_io_min() for statx block size
Message-ID: <20241118070805.GA932@lst.de>
References: <20241113094727.1497722-1-mcgrof@kernel.org> <20241113094727.1497722-9-mcgrof@kernel.org>
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User-Agent: Mutt/1.5.17 (2007-11-01)

On Wed, Nov 13, 2024 at 01:47:27AM -0800, Luis Chamberlain wrote:
> The min-io is the minimum IO the block device prefers for optimal
> performance. In turn we map this to the block device block size.

It's not the block size, but (to quote the man page) 'the "preferred"
block size for efficient filesystem I/O'.  While the difference might
sound minor it actually is important.

> 
> diff --git a/block/bdev.c b/block/bdev.c
> index 3a5fd65f6c8e..4dcc501ed953 100644
> --- a/block/bdev.c
> +++ b/block/bdev.c
> @@ -1306,6 +1306,7 @@ void bdev_statx(struct path *path, struct kstat *stat,
>  			queue_atomic_write_unit_max_bytes(bd_queue));
>  	}
>  
> +	stat->blksize = (unsigned int) bdev_io_min(bdev);

No need for the cast.

>  	if (S_ISBLK(stat->mode))
> -		bdev_statx(path, stat, request_mask);
> +		bdev_statx(path, stat, request_mask | STATX_DIOALIGN);

And this is both unrelated and wrong.