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Subject: Re: [PATCH 0/5] md: fix/prevent dm-raid regressions
To: Song Liu <song@kernel.org>, Yu Kuai <yukuai1@huaweicloud.com>,
 Mikulas Patocka <mpatocka@redhat.com>
Cc: dm-devel@lists.linux.dev, msnitzer@redhat.com, heinzm@redhat.com,
 linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org,
 yi.zhang@huawei.com, yangerkun@huawei.com, "yukuai (C)" <yukuai3@huawei.com>
References: <20240120103734.4155446-1-yukuai1@huaweicloud.com>
 <CAPhsuW7trizGqWcBWQ1R1mrxyA6sNTuwXOK-0vxtCHO6fqcTbQ@mail.gmail.com>
From: Yu Kuai <yukuai1@huaweicloud.com>
Message-ID: <2e1e8e5d-b1c6-efc9-c783-06ce728cd12e@huaweicloud.com>
Date: Mon, 22 Jan 2024 09:19:08 +0800
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Hi,

在 2024/01/21 12:41, Song Liu 写道:
> On Sat, Jan 20, 2024 at 2:41 AM Yu Kuai <yukuai1@huaweicloud.com> wrote:
>>
>> From: Yu Kuai <yukuai3@huawei.com>
>>
>> There are some problems that we fixed in md/raid, and some apis is changed.
>> However, dm-raid rely the old apis(noted that old apis is problematic in
>> corner cases), and now there are regressions in lvm2 testsuite.
>>
>> This patchset fix some regressions(patch 1-3), and revert changes to
>> prevent regressions(patch 4,5). Noted that the problems in patch 4,5 is
>> not clear yet, and I'm not able to locate the root cause ASAP, hence I
>> decide to revert changes to prevent regressions first.
> 
> Thanks for looking into this!
> 
> Patch 1-3 look good to me. But since we need to back port these fixes
> to 6.7 kernels, let's make it very clear what issues are being fixed.
> Please:
> 1. Test on both Linus' master branch and 6.7.y, and explain which tests
> are failing before the fixes. (From my tests, the two branches don't have
> the same test results). We can put these results in the cover letter and
> include them in a merge commit.
> 2. If possible, add Fixes tag to all patches.
> 3. Add more details in the commit log, so it is clear what is being fixed.
> 4. Add "reported-by" and maybe also "closes" tag.
> 

Will do this is the next version. I verified that the following tests
will pass now in my VM:

shell/integrity-caching.sh
shell/lvconvert-raid-reshape.sh

> For patch 4-5, especially 5, I wonder whether the same issue also
> happens with md. We can probably ship 4-5 now, with the same
> improvements as patch 1-3.

With patch 1-3, the test lvconvert-raid-reshape.sh won't hang anymore,
however it still fails and complain that ext4 is corrupted, and I'm
still trying to understand how reshape works in dm-raid. :(
> 
> I will run more tests on my side.

Notice that the problem Mykulas mentioned in the patch md: partially
revert "md/raid6: use valid sector values to determine if an I/O should
wait on the reshape" still exist. And again, I'm stll trying to
understand how raid5 works in detail.
> 
> Mykulas, please also review and test these patches.
> 
> Thanks,
> Song
> 
> 
> 
>>
>> Yu Kuai (5):
>>    md: don't ignore suspended array in md_check_recovery()
>>    md: don't ignore read-only array in md_check_recovery()
>>    md: make sure md_do_sync() will set MD_RECOVERY_DONE
>>    md: revert commit fa2bbff7b0b4 ("md: synchronize flush io with array
>>      reconfiguration") for dm-raid
>>    md: use md_reap_sync_thread() directly for dm-raid
>>
>>   drivers/md/md.c | 58 ++++++++++++++++++++++++++++++-------------------
>>   1 file changed, 36 insertions(+), 22 deletions(-)
>>
>> --
>> 2.39.2
>>
>>
> .
>