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From: Qu Wenruo <quwenruo.btrfs@gmx.com>
To: dsterba@suse.cz, Josef Bacik <josef@toxicpanda.com>,
	linux-btrfs@vger.kernel.org, kernel-team@fb.com
Subject: Re: [PATCH] btrfs: honor path->skip_locking in backref code
Date: Thu, 17 Jan 2019 22:38:26 +0800	[thread overview]
Message-ID: <3ce5bb05-5005-62f7-5174-4c7f3ebd7f8c@gmx.com> (raw)
In-Reply-To: <20190117143021.GR2900@twin.jikos.cz>


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On 2019/1/17 下午10:30, David Sterba wrote:
> On Thu, Jan 17, 2019 at 09:04:13AM +0800, Qu Wenruo wrote:
>>
>>
>> On 2019/1/17 上午12:00, Josef Bacik wrote:
>>> qgroups will do the old roots lookup at delayed ref time, which could be
>>> while walking down the extent root while running a delayed ref.  This
>>> should be fine, except we specifically lock eb's in the backref walking
>>> code irrespective of path->skip_locking, which deadlocks the system.
>>> Fix up the backref code to honor path->skip_locking, nobody will be
>>> modifying the commit_root when we're searching so it's completely safe
>>> to do.  Thanks,
>>>
>>> Signed-off-by: Josef Bacik <josef@toxicpanda.com>
>>
>> Reviewed-by: Qu Wenruo <wqu@suse.com>
> 
> What can we use from https://patchwork.kernel.org/patch/10725371/ to
> add to the changelog? Is the deadlock caused by fb235dc06fac?

The error and cause part should be the same.

Just Josef's is much better than my patch.

Only the [FIX] part needs some update.

Thanks
Qu

> The fix
> applies to stable 4.19+ directly and to 4.14 with context fixups.
> Thanks.
> 


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  reply	other threads:[~2019-01-17 14:38 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-16 16:00 [PATCH] btrfs: honor path->skip_locking in backref code Josef Bacik
2019-01-17  1:04 ` Qu Wenruo
2019-01-17 14:30   ` David Sterba
2019-01-17 14:38     ` Qu Wenruo [this message]
2019-01-17 15:23       ` David Sterba
2019-01-18 13:39 ` David Sterba
2019-01-23 13:51 ` David Sterba
2019-02-12  5:07 ` Qu Wenruo
2019-02-12 14:19   ` David Sterba
2019-02-12 14:25     ` Qu Wenruo
2019-05-28 10:15 Qu Wenruo
2019-05-28 16:10 ` David Sterba
2019-05-28 10:18 Qu Wenruo
2019-05-28 16:10 ` David Sterba

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