Big changes are coming for openSUSE Tumbleweed users who rely on the Bcachefs filesystem. openSUSE has decided to disable Bcachefs starting with kernel 6.18.
All openSUSE Tumbleweed users who are currently using Bcachefs are strongly advised to take necessary precautions due to its upcoming disabling.
But, why this is happening and what to do next? Read on.
Table of Contents
Why Did openSUSE Make This Decision?
The main reason for openSUSE's action stems from a broader decision within the Linux kernel community.
Linus Torvalds, the creator of Linux, publicly commented on potentially removing Bcachefs from the kernel. Consequently, the Linux kernel marked Bcachefs as "externally maintained" since version 6.17.
openSUSE generally does not maintain filesystems marked as "externally maintained". Therefore, the developers discussed the situation and decided to disable it.
Jiri Slaby from SUSE Labs directly stated that openSUSE will re-enable Bcachefs "Once the BCacheFS maintainer behaves and the code is maintained upstream again".
This clearly shows that the decision connects directly to the Bcachefs maintainer's conduct.
Bcachefs Will Be Disabled in Kernel 6.18
Initially, openSUSE planned to disable Bcachefs in kernel 6.17. However, Kent Overstreet, the Bcachefs maintainer, asked for a delay.
He explained that a DKMS module for Bcachefs would not be ready for 6.17. He also emphasized that the Bcachefs version in kernel 6.16 remained very stable, so no immediate urgency existed.
After talking with Kent, openSUSE agreed to postpone the change. Thus, they will disable Bcachefs only in kernel 6.18.
As this unfolds, openSUSE now includes a warning message directly in the kernel: "bcachefs will be removed from the SUSE kernel in 6.18.".
This warning also cautions that the kernel might miss critical Bcachefs fixes because it moved to "externally maintained" status.
It strongly recommends migrating your data, as openSUSE cannot guarantee an externally supported module will be available.
openSUSE Team Says DKMS Modules are Not Preferred
While Kent Overstreet mentioned shipping Bcachefs as a DKMS module, Jiri Slaby explicitly stated that "DKMS modules are not preferred in SUSE".
This is because they "do not rebuild with kernel releases and TW does not have a stable kABI", making them problematic for a rolling release distribution like Tumbleweed.
Therefore, switching away from Bcachefs is a recommended course of action for openSUSE users facing these changes.
A Look at the Deeper Conflict
The decision to mark Bcachefs as "externally maintained" in the mainline kernel stems from significant disagreements.
Linus Torvalds expressed discomfort and announced that he and Kent Overstreet were "done" with their working relationship. He also complained about Kent's communication style in multiple occasions.
Other key kernel developers like Josef Bacik (Btrfs maintainer) and Theodore Ts'o (Ext4 maintainer) have openly criticized Kent Overstreet's "toxic behaviour" and "silly childishness".
They clearly stated that the problem is not Bcachefs's technical quality. Instead, it comes from Kent's interactions, which they say "undermin[e] the health of the community".
Sasha Levin further stressed that "A toxic community that drives away contributors fails its users far more severely than the absence of any single filesystem ever could".
Kent Overstreet, on the other hand, calls it a "management issue". He criticizes what he sees as a lack of "engineering standards" in the Linux filesystem world, particularly concerning Btrfs's reliability.
He maintains that Bcachefs offers "better reliability than Ext4/XFS" and "much better reliability" than Btrfs, a claim supported by some users.
Kent Overstreet stated he felt "attacked" by pressure from upstream developers, explaining that this caused his "sharp" responses.
He then offered to stop criticizing Btrfs and other kernel code if Linus Torvalds would stop dictating terms on Bcachefs's internal patches
User Impact and Next Steps
This news deeply affects many users. Some, like Malte Schröder, express disappointment, noting Bcachefs's stability and fixed issues. Other users run Bcachefs in production and worry about their data.
Gerhard Wiesinger, a user, confirmed that Bcachefs remains stable and successfully repaired data corruption in tests where Btrfs could not.
Another user, Peter Schneider, remarked that removing Bcachefs would "hurt Linux users" and greatly "violate the promise to not break userspace".
Despite the user support and technical appreciation for Bcachefs, openSUSE will disable it starting from kernel 6.18.
Therefore, if you use Bcachefs on openSUSE Tumbleweed, you should plan for migration. Here are your options:
- Migrate Your Data: openSUSE strongly recommends moving your data from Bcachefs to another supported filesystem.
- Switch to Slowroll: You can temporarily switch to the slowroll kernel, which currently runs kernel 6.12. However, this code will eventually become outdated.
- Consider a KMP: If you really need Bcachefs, you or other community members might prepare a Kernel Module Package (KMP) for it. Remember, though, openSUSE typically avoids DKMS modules due to rebuilding challenges and Tumbleweed's unstable kernel ABI.
Looking Ahead
This situation shows the complexities of open-source development, where technical brilliance sometimes meets interpersonal hurdles.
While Bcachefs boasts promising features and a dedicated user base, its future in the mainline Linux kernel, and thus in openSUSE, now depends on resolving these community-level issues.
Stay tuned for more updates!
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