Re: Mixed inline and regular extents caused by btrfs/062

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

On 2021/8/10 下午3:46, Nikolay Borisov wrote:
>
>
> On 10.08.21 г. 8:49, Qu Wenruo wrote:
>> Hi,
>>
>> Although I understand current kernel can handle mixed inline extent with
>> regular extent without problem, but the idea of mixing them is still
>> making me quite unease.
>>
>> Thus I still go testing with modify btrfs-progs to detect such problem,
>> and find out btrfs/062 can cause such mixed extents.
>>
>> Since it's not really causing any on-disk data corruption, but just an
>> inconsistent behavior, I'm wondering do we really need to fix it.
>> (This is also the only reason why subpage has disabled inline extent
>> creation completely, just to prevent such problem).
>>
>> Any idea on whether we should "fix" the behavior?
>
> What do you mean by mixed inline and regular extents?

I mean, one inode has both inlined extent and regular extent.

There is an old btrfs-progs patch to detect such problems:

https://patchwork.kernel.org/project/linux-btrfs/patch/20210504062525.152540-3-wqu@suse.com/


> AFAICS inline
> extents are created when you write at the beginning of the file and the
> size of the write is less than the inline extent threshold? All
> subsequent writes are going to be regular extents.

But with above patch, the following test cases can cause btrfs-check to
report such mixed inline and regular extents:

btrfs/004
btrfs/192
btrfs/195
btrfs/205
generic/269

(Haven't yet to check the reproducibility)

Currently it won't hurt anyone, but I still don't think the mixed
behavior is expected.

Thanks,
Qu
>
>>
>> Thanks,
>> Qu
>>