Bcachefs Relaunches with DKMS Packages After Linux Kernel Exclusion; Early Benchmarks Show Major Performance Gains
The bcachefs filesystem, now developed outside the Linux kernel, has released its first set of packages for live loading via DKMS. This move came in response to the community’s decision: in kernel version 6.17, the bcachefs code remained unchanged from 6.16, while Kent Overstreet had already promised weeks earlier that the new version would be made available independently of the mainline branch.
The new packages are distributed through an APT repository, currently limiting their use to the Ubuntu and Debian families. In essence, this is the code that was meant to be integrated into kernel 6.17, but was ultimately excluded by Linus Torvalds in August. As a result, testers of the 6.17 release candidates now face two flavors of bcachefs: the built-in version, identical to 6.16, and the alternative DKMS-loaded module.
A Phoronix benchmark series on in-kernel filesystems in 6.17 did not reflect well on bcachefs: across 16 tests, it ranked at or near the bottom. However, repeated trials with the new DKMS build showed performance doubling, pushing it into the middle tier of results. The filesystem remains young and far from fully optimized, but the progress is unmistakable.
A separate situation has unfolded around openSUSE. Initially, the distribution had signaled plans to drop bcachefs support. Yet after Overstreet engaged with project maintainers, their stance softened. A kernel patch for openSUSE now displays a warning that bcachefs will be removed in version 6.18. Discussions in Bugzilla and the Factory mailing list clarified that support will persist in Tumbleweed with the transition to kernel 6.17, with final removal expected only in 6.18.
Still, the project faces fresh threats. Community veteran Christoph Hellwig submitted a patch to linux-next removing the write_cache_pages API starting with 6.18. In his view, once bcachefs was excluded, the API was no longer needed. Meanwhile, NTFS3 has already been integrated, while OpenZFS remains excluded due to licensing issues. Such a change could significantly complicate life for out-of-tree filesystems, forcing them to devise workarounds.
Tensions within the community are hardly new: Hellwig is known for his uncompromising positions. He previously accused VMware of GPL violations, even pursuing the matter in court, and in early 2025 he compared the inclusion of Rust in the kernel to cancer.
Additional friction around bcachefs stems from personal conflicts. Josef Bacik, a Meta developer and vocal critic of Overstreet who championed Btrfs, announced in August that he was leaving Meta and ceasing his kernel work. He now intends to join Anthropic.
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