linux-kernel - Re: [PATCH v4 6/9] md/raid1,raid10: Fix missing retries Failfast write bios on no-bbl rdevs

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Message-ID: <cd9aa561-7a0a-3400-1896-8afed3d7cbb3@huaweicloud.com>
Date: Wed, 17 Sep 2025 18:06:33 +0800
From: Li Nan <linan666@...weicloud.com>
To: Kenta Akagi <k@...l.me>, Song Liu <song@...nel.org>,
 Yu Kuai <yukuai3@...wei.com>, Mariusz Tkaczyk <mtkaczyk@...nel.org>,
 Shaohua Li <shli@...com>, Guoqing Jiang <jgq516@...il.com>
Cc: linux-raid@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 6/9] md/raid1,raid10: Fix missing retries Failfast
 write bios on no-bbl rdevs



在 2025/9/15 11:42, Kenta Akagi 写道:
> In the current implementation, write failures are not retried on rdevs
> with badblocks disabled. This is because narrow_write_error, which issues
> retry bios, immediately returns when badblocks are disabled. As a result,
> a single write failure on such an rdev will immediately mark it as Faulty.
> 

IMO, there's no need to add extra logic for scenarios where badblocks
is not enabled. Do you have real-world scenarios where badblocks is
disabled?

> The retry mechanism appears to have been implemented under the assumption
> that a bad block is involved in the failure. However, the retry after
> MD_FAILFAST write failure depend on this code, and a Failfast write request
> may fail for reasons unrelated to bad blocks.
> 
> Consequently, if failfast is enabled and badblocks are disabled on all
> rdevs, and all rdevs encounter a failfast write bio failure at the same
> time, no retries will occur and the entire array can be lost.
> 
> This commit adds a path in narrow_write_error to retry writes even on rdevs
> where bad blocks are disabled, and failed bios marked with MD_FAILFAST will
> use this path. For non-failfast cases, the behavior remains unchanged: no
> retry writes are attempted to rdevs with bad blocks disabled.
> 
> Fixes: 1919cbb23bf1 ("md/raid10: add failfast handling for writes.")
> Fixes: 212e7eb7a340 ("md/raid1: add failfast handling for writes.")
> Signed-off-by: Kenta Akagi <k@...l.me>
> ---
>   drivers/md/raid1.c  | 44 +++++++++++++++++++++++++++++---------------
>   drivers/md/raid10.c | 37 ++++++++++++++++++++++++-------------
>   2 files changed, 53 insertions(+), 28 deletions(-)
> 				 !test_bit(Faulty, &rdev->flags) &&

-- 
Thanks,
Nan