Re: [GIT PULL] bcachefs changes for 6.17

Martin Steigerwald
2025-08-10T10:32:41Z

Hi Gerhard, hi.

Gerhard Wiesinger - 10.08.25, 08:20:43 CEST:
> On 28.07.2025 17:14, Kent Overstreet wrote:
> > Schedule notes for users:
> >
> > I've been digging through the bug tracker and polling users to see
> > what bugs are still outstanding, and - it's not much.
> >
> > So, the experimental label is coming off in 6.18.
> >
> > As always, if you do hit a bug, please report it.
>
> I can now confirm that bcachefs is getting stable and the test cases
> with intentionally data corruption (simulation of a real world case I
> had) gets bcachefs back to a consistent state (after 2 runs of: bcachefs
> fsck -f -y ${DEV}). That's a base requirement for a stable filesystem.
> Version of bcachefs-tools is git
> 530e8ade4e6af7d152f4f79bf9f2b9dec6441f2b and kernel is
> 6.16.0-200.fc42.x86_64.
>
> See for details, I made data corruption even worser with running the
> destroy script 5x:
>
> https://lore.kernel.org/linux-bcachefs/aa613c37-153c-43e4-b68e-9d50744be
> 7de@wiesinger.com/
>
> Great work Kent and the other contributors.
>
> Unfortunately btrfs can't be repaired to a consistent state with the
> same testcase. I'd like to be that testcase fixed also for BTRFS as a
> stable filesystem (versions: 6.16.0-200.fc42.x86_64, btrfs-progs v6.15,
> -EXPERIMENTAL -INJECT -STATIC +LZO +ZSTD +UDEV +FSVERITY +ZONED
> CRYPTO=libgcrypt).
>
> (I reported that already far in the past on the mailing list, see here:
> https://lore.kernel.org/linux-btrfs/63f8866f-ceda-4228-b595-e37b016e7b1f
> @wiesinger.com/).

Thanks for this great find and these test results.

On a technical perspective I still think the Linux kernel is a better
kernel with BCacheFS included.

And write this without having had any issues – except for bad performance
especially on hard disks, but partly also on flash – with BTRFS. And I use
it on a couple laptops, some virtual machines and a lot of external disks.
But not on a multi device setup. I had a BTRFS RAID 1 for a long time.
This also has been stable since kernel 4.6 up to the time I still used it.

So I did not really have much of a need to fsck BTRFS.

Best,
--
Martin