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Subject: Re: [PATCH 2/2] md/raid10: handle replacement devices in
 fix_recovery_read_error
To:     Song Liu <song@kernel.org>, linan666@huaweicloud.com
Cc:     linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org,
        linan122@huawei.com, yi.zhang@huawei.com, houtao1@huawei.com,
        yangerkun@huawei.com, "yukuai (C)" <yukuai3@huawei.com>
References: <20230627034127.4000994-1-linan666@huaweicloud.com>
 <20230627034127.4000994-3-linan666@huaweicloud.com>
 <CAPhsuW7+bWe9YDMnjRgb657Fz7Vs_4wnBcU9jVSXuofKhaO38Q@mail.gmail.com>
From:   Yu Kuai <yukuai1@huaweicloud.com>
Message-ID: <62e6e2bc-4fd2-0ee9-6215-609778e0289a@huaweicloud.com>
Date:   Mon, 10 Jul 2023 21:00:31 +0800
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Hi,

在 2023/07/07 16:33, Song Liu 写道:
> On Tue, Jun 27, 2023 at 11:42 AM <linan666@huaweicloud.com> wrote:
>>
>> From: Li Nan <linan122@huawei.com>
>>
>> In fix_recovery_read_error(), the handling of replacement devices is
>> missing. Add it. If io error is from replacement, error this device
>> directly. If io error is from other device, just set badblocks for
>> replacement.
>>
>> Signed-off-by: Li Nan <linan122@huawei.com>
>> ---
>>   drivers/md/raid10.c | 10 ++++++++--
>>   1 file changed, 8 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
>> index 5105273f60e9..6d9025089455 100644
>> --- a/drivers/md/raid10.c
>> +++ b/drivers/md/raid10.c
>> @@ -2551,7 +2551,7 @@ static void fix_recovery_read_error(struct r10bio *r10_bio)
>>
>>          while (sectors) {
>>                  int s = sectors;
>> -               struct md_rdev *rdev;
>> +               struct md_rdev *rdev, *repl;
>>                  sector_t addr;
>>                  int ok;
>>
>> @@ -2559,6 +2559,7 @@ static void fix_recovery_read_error(struct r10bio *r10_bio)
>>                          s = PAGE_SIZE >> 9;
>>
>>                  rdev = conf->mirrors[dr].rdev;
>> +               repl = conf->mirrors[dw].replacement;
>>                  addr = r10_bio->devs[0].addr + sect,
>>                  ok = sync_page_io(rdev,
>>                                    addr,
>> @@ -2580,6 +2581,9 @@ static void fix_recovery_read_error(struct r10bio *r10_bio)
>>                                          set_bit(MD_RECOVERY_NEEDED,
>>                                                  &rdev->mddev->recovery);
>>                          }
>> +                       if (repl && !sync_page_io(repl, addr, s << 9,
>> +                           pages[idx], REQ_OP_WRITE, false))
>> +                               md_error(mddev, repl);
>>                  }
>>                  if (!ok) {
>>                          /* We don't worry if we cannot set a bad block -
>> @@ -2592,7 +2596,9 @@ static void fix_recovery_read_error(struct r10bio *r10_bio)
>>                                  /* need bad block on destination too */
>>                                  rdev = conf->mirrors[dw].rdev;
>>                                  addr = r10_bio->devs[1].addr + sect;
>> -                               if (!rdev_set_badblocks(rdev, addr, s, 0)) {
>> +                               if (!rdev_set_badblocks(rdev, addr, s, 0) ||
>> +                                   (repl &&
>> +                                   !rdev_set_badblocks(repl, addr, s, 0))) {
> 
> Do we really want this in the if () statement? Shall we always set
> badblock on both rdev and repl?

I think this is wrong to set repl badblocks inside this, because if
setting badblocks for rdev failed, repl is still not handled.

By the way, I think it's better to at least try to read from all
possible copies before setting badblocks for repl.

Thanks,
Kuai
> 
> Thanks,
> Song
> 
>>                                          /* just abort the recovery */
>>                                          pr_notice("md/raid10:%s: recovery aborted due to read error\n",
>>                                                    mdname(mddev));
>> --
>> 2.39.2
>>
> .
>