Re: [PATCH] md: fix bi_status reporting in md_end_clone_io

[Guoqing Jiang <guoqing.jiang@linux.dev>]

On 11/18/23 08:39, Song Liu wrote:
> md_end_clone_io() may overwrite error status in orig_bio->bi_status with
> BLK_STS_OK. This could happen when orig_bio has BIO_CHAIN (split by
> md_submit_bio => bio_split_to_limits, for example). As a result, upper
> layer may miss error reported from md (or the device) and consider the
> failed IO was successful.
>
> Fix this by only update orig_bio->bi_status when current bio reports
> error and orig_bio is BLK_STS_OK. This is the same behavior as
> __bio_chain_endio().

DRBD has the similar change.

> Fixes: 10764815ff47 ("md: add io accounting for raid0 and raid5")
> Reported-by: Bhanu Victor DiCara <00bvd0+linux@gmail.com>
> Closes: https://lore.kernel.org/regressions/5727380.DvuYhMxLoT@bvd0/
> Signed-off-by: Song Liu <song@kernel.org>
> Tested-by: Xiao Ni <xni@redhat.com>
> Cc: Guoqing Jiang <guoqing.jiang@linux.dev>
> ---
>   drivers/md/md.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 4ee4593c874a..c94373d64f2c 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -8666,7 +8666,8 @@ static void md_end_clone_io(struct bio *bio)
>   	struct bio *orig_bio = md_io_clone->orig_bio;
>   	struct mddev *mddev = md_io_clone->mddev;
>   
> -	orig_bio->bi_status = bio->bi_status;
> +	if (bio->bi_status && !orig_bio->bi_status)
> +		orig_bio->bi_status = bio->bi_status;

Thanks for the fix!

Acked-by: Guoqing Jiang <guoqing.jiang@linux.dev>

Guoqing