Re: [REGRESSION][BISECTED] Spurious raid1 device failure triggered by qemu direct IO on 6.18+

[Keith Busch <kbusch@kernel.org>]

On Wed, Apr 15, 2026 at 09:52:12AM -0600, Keith Busch wrote:
> Suggest the stacking layers shouldn't consider BLK_STS_INVAL to be a
> device error or retryable.

I was able to recreate the reported issue (the key is you have to use
dm-raid, not md-raid), and the below diff tests successfully for me.
I'll send a formal patch tomorrow.

> ---
> diff --git a/drivers/md/raid1-10.c b/drivers/md/raid1-10.c
> index c33099925f230..cf1c25f290f36 100644
> --- a/drivers/md/raid1-10.c
> +++ b/drivers/md/raid1-10.c
> @@ -293,8 +293,16 @@ static inline bool raid1_should_read_first(struct mddev *mddev,
>   * bio with REQ_RAHEAD or REQ_NOWAIT can fail at anytime, before such IO is
>   * submitted to the underlying disks, hence don't record badblocks or retry
>   * in this case.
> + *
> + * BLK_STS_INVAL means the request itself is malformed (e.g. unaligned
> + * buffers that violate DMA constraints).  Retrying on another mirror will
> + * fail the same way, and counting it against the device is wrong.
>   */
>  static inline bool raid1_should_handle_error(struct bio *bio)
>  {
> -	return !(bio->bi_opf & (REQ_RAHEAD | REQ_NOWAIT));
> +	if (bio->bi_opf & (REQ_RAHEAD | REQ_NOWAIT))
> +		return false;
> +	if (bio->bi_status == BLK_STS_INVAL)
> +		return false;
> +	return true;
>  }
> --
>