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Subject: Re: Transaction aborted (error -17) after crash
To: Mordechay Kaganer <mkaganer@gmail.com>,
        Qu Wenruo <quwenruo@cn.fujitsu.com>
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From: Qu Wenruo <quwenruo.btrfs@gmx.com>
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Date: Wed, 18 Nov 2015 20:28:57 +0800
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在 2015年11月18日 20:02, Mordechay Kaganer 写道:
> B.H.
>
> On Wed, Nov 18, 2015 at 7:31 AM, Qu Wenruo <quwenruo@cn.fujitsu.com> wrote:
>>
>> Hard to say yet.
>>
>> Is that the only error?
>>
>> And did you tried btrfsck --init-extent-tree alone?
>> Although IIRC --init-extent-tree implies --repair, but it seems that extent
>> tree is not correctly rebuilt at least.
>
> btrfs check --init-extent-tree --repair gives tons of messages like this:
>
> ref mismatch on [1628438528 16384] extent item 0, found 1
> adding new tree backref on start 1628438528 len 16384 parent 0 root 258
> Backref 1628438528 parent 258 root 258 not found in extent tree
> backpointer mismatch on [1628438528 16384]
> ref mismatch on [1628454912 16384] extent item 0, found 1
> adding new tree backref on start 1628454912 len 16384 parent 0 root 7
> Backref 1628454912 parent 7 root 7 not found in extent tree
> backpointer mismatch on [1628454912 16384]
> ref mismatch on [1628471296 16384] extent item 0, found 1
> adding new tree backref on start 1628471296 len 16384 parent 0 root 7
> Backref 1628471296 parent 7 root 7 not found in extent tree
> backpointer mismatch on [1628471296 16384]
> ref mismatch on [1628487680 16384] extent item 0, found 1
> adding new tree backref on start 1628487680 len 16384 parent 0 root 7
> Backref 1628487680 parent 7 root 7 not found in extent tree
> backpointer mismatch on [1628487680 16384]
>
> Anyway, that's only a backup so i think it's better to rebuild it from
> scratch, right?
>
If it's OK for you, then it's OK

BTW, did you run btrfsck *after* --init-extent-tree, *without* --repair?
I think it would be much better to do the last btrfsck.

And if the last one reports no error, and btrfs still hits the same 
problem, I think it's time to rebuild the backup....

Thanks,
Qu