linux-kernel - Re: [PATCH] md/raid1: fix data lost for writemostly rdev

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Message-ID: <f95856f8-117a-9b4a-f417-d65f951931c5@huaweicloud.com>
Date: Wed, 3 Sep 2025 11:23:17 +0800
From: Li Nan <linan666@...weicloud.com>
To: Yu Kuai <yukuai1@...weicloud.com>, song@...nel.org,
 ian@...are.dropbear.id.au
Cc: linux-raid@...r.kernel.org, linux-kernel@...r.kernel.org,
 yukuai3@...wei.com, yi.zhang@...wei.com, yangerkun@...wei.com,
 johnny.chenyi@...wei.com
Subject: Re: [PATCH] md/raid1: fix data lost for writemostly rdev



在 2025/9/3 9:41, Yu Kuai 写道:
> From: Yu Kuai <yukuai3@...wei.com>
> 
> If writemostly is enabled, alloc_behind_master_bio() will allocate a new
> bio for rdev, with bi_opf set to 0. Later, raid1_write_request() will
> clone from this bio, hence bi_opf is still 0 for the cloned bio. Submit
> this cloned bio will end up to be read, causing write data lost.
> 
> Fix this problem by inheriting bi_opf from original bio for
> behind_mast_bio.
> 
> Fixes: e879a0d9cb08 ("md/raid1,raid10: don't ignore IO flags")
> Reported-and-tested-by: Ian Dall <ian@...are.dropbear.id.au>
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220507
> Signed-off-by: Yu Kuai <yukuai3@...wei.com>
> ---
>   drivers/md/raid1.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
> index f8434049f9b1..f391fd56d67f 100644
> --- a/drivers/md/raid1.c
> +++ b/drivers/md/raid1.c
> @@ -1225,7 +1225,7 @@ static void alloc_behind_master_bio(struct r1bio *r1_bio,
>   	int i = 0;
>   	struct bio *behind_bio = NULL;
>   
> -	behind_bio = bio_alloc_bioset(NULL, vcnt, 0, GFP_NOIO,
> +	behind_bio = bio_alloc_bioset(NULL, vcnt, bio->bi_opf, GFP_NOIO,
>   				      &r1_bio->mddev->bio_set);
>   
>   	/* discard op, we don't support writezero/writesame yet */

LGTM

Reviewed-by: Li Nan <linan122@...wei.com>
-- 
Thanks,
Nan