linux-kernel - Re: [PATCH 11/13] xfs: expose block size in stat

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Date: Mon, 26 Feb 2024 23:44:16 +1100
From: Dave Chinner <david@...morbit.com>
To: "Pankaj Raghav (Samsung)" <kernel@...kajraghav.com>
Cc: linux-xfs@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org, chandan.babu@...cle.com,
	akpm@...ux-foundation.org, mcgrof@...nel.org, ziy@...dia.com,
	hare@...e.de, djwong@...nel.org, gost.dev@...sung.com,
	linux-mm@...ck.org, willy@...radead.org,
	Dave Chinner <dchinner@...hat.com>
Subject: Re: [PATCH 11/13] xfs: expose block size in stat

On Mon, Feb 26, 2024 at 10:49:34AM +0100, Pankaj Raghav (Samsung) wrote:
> From: Dave Chinner <dchinner@...hat.com>
> 
> For block size larger than page size, the unit of efficient IO is
> the block size, not the page size. Leaving stat() to report
> PAGE_SIZE as the block size causes test programs like fsx to issue
> illegal ranges for operations that require block size alignment
> (e.g. fallocate() insert range). Hence update the preferred IO size
> to reflect the block size in this case.
> 
> Signed-off-by: Dave Chinner <dchinner@...hat.com>
> dd2d535e3fb29d ("xfs: cleanup calculating the stat optimal I/O size")]
> Signed-off-by: Luis Chamberlain <mcgrof@...nel.org>

Something screwed up there, and you haven't put your own SOB on
this.

> ---
>  fs/xfs/xfs_iops.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
> index a0d77f5f512e..1b4edfad464f 100644
> --- a/fs/xfs/xfs_iops.c
> +++ b/fs/xfs/xfs_iops.c
> @@ -543,7 +543,7 @@ xfs_stat_blksize(
>  			return 1U << mp->m_allocsize_log;
>  	}
>  
> -	return PAGE_SIZE;
> +	return max_t(unsigned long, PAGE_SIZE, mp->m_sb.sb_blocksize);
>  }

This function returns a uint32_t, same type as
mp->m_sb.sb_blocksize. The comparision should use uint32_t casts,
not unsigned long.

ALso, this bears no resemblence to the original patch I wrote back in
2018. Please remove my SOB from it - you can state that "this change
is based on a patch originally from Dave Chinner" to credit the
history of it, but it's certainly not the patch I wrote 6 years ago
and so my SOB does not belong on it.

-Dave.
-- 
Dave Chinner
david@...morbit.com