Re: [PATCH 3/3] btrfs-progs: tune: add fsck runs before and after a full conversion

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

On 2023/12/6 03:16, David Sterba wrote:
> On Mon, Dec 04, 2023 at 08:52:15PM +1030, Qu Wenruo wrote:
>>> And maybe an option to skip check? People who want to convert to BG tree
>>> usually have large filesystems, then the original check can be killed
>>> because of OOM...
>>
>> I don't want to allow it to be skipped. Maybe I can add some logic to go
>> lowmem mode depending on the filesystem size.
>
> We have power users who know what they're doing and no way to skip the
> check is considered a usability bug. The check can fail for reasons that
> may not be due to detected problems but due to lack of memory. The
> heuristic regarding lowmem or original mode does not sound like a good
> idea to me, it seems too unreliable.

That's true.

>
>> Just don't want to risk any possible corruption.
>
> Instead of forcing the check in all cases, by default it can skip the
> conversion and print a warning with and recommendation to run check.
> With an option to override it it would start right away.
>

So you mean without any special option, the btrfstune for bgt/csum
change would be no-op but only outputting a warning?

This would be stronger than the 10s delay of btrfs check, and require
less work (no need to export btrfs check).

But I'm not that confident if most users would even follow the
recommendation...

Thanks,
Qu