Re: [PATCH 0/5] raid56: variant bug fixes

From: Qu Wenruo <quwenruo@cn.fujitsu.com>
To: <linux-btrfs@vger.kernel.org>, David Sterba <dsterba@suse.com>,
	Chris Mason <clm@fb.com>
Subject: Re: [PATCH 0/5] raid56: variant bug fixes
Date: Tue, 7 Mar 2017 11:48:37 +0800	[thread overview]
Message-ID: <b6ba2bec-ea6c-ca7f-5806-ba6c6dfc71f7@cn.fujitsu.com> (raw)
In-Reply-To: <20170203082023.3577-1-quwenruo@cn.fujitsu.com>

So raid56 bug fixes are the same case as qgroup fixes now?

No reviewer so no merge?

I understand we need enough reviewer, however there is never enough 
reviewer for *minor* functions, like qgroup or raid56.

Such situation will just make such functions starve, bugs makes fewer 
tester and users, fewer users leads to even fewer developers, causing a 
minus spiral.

Thanks,
Qu

At 02/03/2017 04:20 PM, Qu Wenruo wrote:
> This patchset can be fetched from my github repo:
> https://github.com/adam900710/linux.git raid56_fixes
>
> It's based on v4.10-rc6 and none of the patch is modified after its first
> appearance in mail list.
>
> The patchset fixes the following bugs:
>
> 1) False alert or wrong csum error number when scrubbing RAID5/6
>    The bug itself won't cause any damage to fs, just pure race.
>
> 2) Corrupted data stripe rebuild corrupts P/Q
>    So scrub makes one error into another, not really fixing anything
>
> 3) Use-after-free caused by cancelling dev-replace
>    This is quite a deadly bug, since cancelling dev-replace can easily
>    cause kernel panic, and thanks to raid bio steal, it makes the race
>    windows quite large.
>
>    Can be triggered by btrfs/069.
>
> After all the fixes applied, no scrub/replace related regression can be
> detected.
>
> Qu Wenruo (5):
>   btrfs: scrub: Introduce full stripe lock for RAID56
>   btrfs: scrub: Fix RAID56 recovery race condition
>   btrfs: raid56: Use correct stolen pages to calculate P/Q
>   btrfs: raid56: Don't keep rbio for later steal
>   btrfs: replace: Use ref counts to avoid destroying target device when
>     canceled
>
>  fs/btrfs/ctree.h       |   4 ++
>  fs/btrfs/dev-replace.c |   7 +-
>  fs/btrfs/extent-tree.c |   3 +
>  fs/btrfs/raid56.c      |  80 +++++++++++++++------
>  fs/btrfs/scrub.c       | 192 +++++++++++++++++++++++++++++++++++++++++++++++++
>  fs/btrfs/volumes.c     |  36 +++++++++-
>  fs/btrfs/volumes.h     |  10 +++
>  7 files changed, 309 insertions(+), 23 deletions(-)
>